Source/WebCore/rendering/RenderBox.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005-2010, 2015 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */

 #include "config.h"
 #include "RenderBox.h"

 #include "CSSFontSelector.h"
 #include "ControlStates.h"
 #include "Document.h"
 #include "Editing.h"
 #include "EventHandler.h"
 #include "FloatQuad.h"
 #include "FloatRoundedRect.h"
 #include "Frame.h"
 #include "FrameView.h"
 #include "GraphicsContext.h"
 #include "HTMLBodyElement.h"
 #include "HTMLButtonElement.h"
 #include "HTMLFrameOwnerElement.h"
 #include "HTMLHtmlElement.h"
 #include "HTMLImageElement.h"
 #include "HTMLInputElement.h"
 #include "HTMLLegendElement.h"
 #include "HTMLNames.h"
 #include "HTMLSelectElement.h"
 #include "HTMLTextAreaElement.h"
 #include "HitTestResult.h"
 #include "InlineElementBox.h"
 #include "Page.h"
 #include "PaintInfo.h"
 #include "RenderBoxFragmentInfo.h"
 #include "RenderChildIterator.h"
 #include "RenderDeprecatedFlexibleBox.h"
 #include "RenderFlexibleBox.h"
 #include "RenderFragmentContainer.h"
 #include "RenderGeometryMap.h"
 #include "RenderGrid.h"
 #include "RenderInline.h"
 #include "RenderIterator.h"
 #include "RenderLayer.h"
 #include "RenderLayerCompositor.h"
 #include "RenderLayoutState.h"
 #include "RenderMultiColumnFlow.h"
 #include "RenderTableCell.h"
 #include "RenderTheme.h"
 #include "RenderView.h"
 #include "RuntimeApplicationChecks.h"
 #include "ScrollAnimator.h"
 #include "ScrollbarTheme.h"
 #include "Settings.h"
 #include "StyleScrollSnapPoints.h"
 #include "TransformState.h"
 #include <algorithm>
 #include <math.h>
 #include <wtf/IsoMallocInlines.h>
 #include <wtf/StackStats.h>

 namespace WebCore {

 WTF_MAKE_ISO_ALLOCATED_IMPL(RenderBox);

 struct SameSizeAsRenderBox : public RenderBoxModelObject {
     virtual ~SameSizeAsRenderBox() = default;
     LayoutRect frameRect;
     LayoutBoxExtent marginBox;
     LayoutUnit preferredLogicalWidths[2];
     void* pointers[2];
 };

 COMPILE_ASSERT(sizeof(RenderBox) == sizeof(SameSizeAsRenderBox), RenderBox_should_stay_small);

 using namespace HTMLNames;

 // Used by flexible boxes when flexing this element and by table cells.
 typedef WTF::HashMap<const RenderBox*, LayoutUnit> OverrideSizeMap;
 static OverrideSizeMap* gOverrideContentLogicalHeightMap = nullptr;
 static OverrideSizeMap* gOverrideContentLogicalWidthMap = nullptr;

 // Used by grid elements to properly size their grid items.
 // FIXME: We should store these based on physical direction.
 typedef WTF::HashMap<const RenderBox*, Optional<LayoutUnit>> OverrideOptionalSizeMap;
 static OverrideOptionalSizeMap* gOverrideContainingBlockContentLogicalHeightMap = nullptr;
 static OverrideOptionalSizeMap* gOverrideContainingBlockContentLogicalWidthMap = nullptr;

 // Size of border belt for autoscroll. When mouse pointer in border belt,
 // autoscroll is started.
 static const int autoscrollBeltSize = 20;
 static const unsigned backgroundObscurationTestMaxDepth = 4;

 using ControlStatesRendererMap = HashMap<const RenderObject*, std::unique_ptr<ControlStates>>;
 static ControlStatesRendererMap& controlStatesRendererMap()
 {
     static NeverDestroyed<ControlStatesRendererMap> map;
     return map;
 }

 static ControlStates* controlStatesForRenderer(const RenderBox& renderer)
 {
     return controlStatesRendererMap().ensure(&renderer, [] {
         return makeUnique<ControlStates>();
     }).iterator->value.get();
 }

 static void removeControlStatesForRenderer(const RenderBox& renderer)
 {
     controlStatesRendererMap().remove(&renderer);
 }

 bool RenderBox::s_hadOverflowClip = false;

 RenderBox::RenderBox(Element& element, RenderStyle&& style, BaseTypeFlags baseTypeFlags)
     : RenderBoxModelObject(element, WTFMove(style), baseTypeFlags)
 {
     setIsBox();
 }

 RenderBox::RenderBox(Document& document, RenderStyle&& style, BaseTypeFlags baseTypeFlags)
     : RenderBoxModelObject(document, WTFMove(style), baseTypeFlags)
 {
     setIsBox();
 }

 RenderBox::~RenderBox()
 {
     // Do not add any code here. Add it to willBeDestroyed() instead.
 }

 void RenderBox::willBeDestroyed()
 {
     if (frame().eventHandler().autoscrollRenderer() == this)
         frame().eventHandler().stopAutoscrollTimer(true);

     clearOverrideContentSize();
     clearOverrideContainingBlockContentSize();

     RenderBlock::removePercentHeightDescendantIfNeeded(*this);

     ShapeOutsideInfo::removeInfo(*this);

     view().unscheduleLazyRepaint(*this);
     removeControlStatesForRenderer(*this);

 #if ENABLE(CSS_SCROLL_SNAP)
     if (hasInitializedStyle() && style().scrollSnapArea().hasSnapPosition())
         view().unregisterBoxWithScrollSnapPositions(*this);
 #endif

     RenderBoxModelObject::willBeDestroyed();
 }

 RenderFragmentContainer* RenderBox::clampToStartAndEndFragments(RenderFragmentContainer* fragment) const
 {
     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();

     ASSERT(isRenderView() || (fragment && fragmentedFlow));
     if (isRenderView())
         return fragment;

     // We need to clamp to the block, since we want any lines or blocks that overflow out of the
     // logical top or logical bottom of the block to size as though the border box in the first and
     // last fragments extended infinitely. Otherwise the lines are going to size according to the fragments
     // they overflow into, which makes no sense when this block doesn't exist in |fragment| at all.
     RenderFragmentContainer* startFragment = nullptr;
     RenderFragmentContainer* endFragment = nullptr;
     if (!fragmentedFlow->getFragmentRangeForBox(this, startFragment, endFragment))
         return fragment;

     if (fragment->logicalTopForFragmentedFlowContent() < startFragment->logicalTopForFragmentedFlowContent())
         return startFragment;
     if (fragment->logicalTopForFragmentedFlowContent() > endFragment->logicalTopForFragmentedFlowContent())
         return endFragment;

     return fragment;
 }

 bool RenderBox::hasFragmentRangeInFragmentedFlow() const
 {
     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (!fragmentedFlow || !fragmentedFlow->hasValidFragmentInfo())
         return false;

     return fragmentedFlow->hasCachedFragmentRangeForBox(*this);
 }

 LayoutRect RenderBox::clientBoxRectInFragment(RenderFragmentContainer* fragment) const
 {
     if (!fragment)
         return clientBoxRect();

     LayoutRect clientBox = borderBoxRectInFragment(fragment);
     clientBox.setLocation(clientBox.location() + LayoutSize(borderLeft(), borderTop()));
     clientBox.setSize(clientBox.size() - LayoutSize(borderLeft() + borderRight() + verticalScrollbarWidth(), borderTop() + borderBottom() + horizontalScrollbarHeight()));

     return clientBox;
 }

 LayoutRect RenderBox::borderBoxRectInFragment(RenderFragmentContainer*, RenderBoxFragmentInfoFlags) const
 {
     return borderBoxRect();
 }

 static RenderBlockFlow* outermostBlockContainingFloatingObject(RenderBox& box)
 {
     ASSERT(box.isFloating());
     RenderBlockFlow* parentBlock = nullptr;
     for (auto& ancestor : ancestorsOfType<RenderBlockFlow>(box)) {
         if (ancestor.isRenderView())
             break;
         if (!parentBlock || ancestor.containsFloat(box))
             parentBlock = &ancestor;
     }
     return parentBlock;
 }

 void RenderBox::removeFloatingOrPositionedChildFromBlockLists()
 {
     ASSERT(isFloatingOrOutOfFlowPositioned());

     if (renderTreeBeingDestroyed())
         return;

     if (isFloating()) {
         if (RenderBlockFlow* parentBlock = outermostBlockContainingFloatingObject(*this)) {
             parentBlock->markSiblingsWithFloatsForLayout(this);
             parentBlock->markAllDescendantsWithFloatsForLayout(this, false);
         }
     }

     if (isOutOfFlowPositioned())
         RenderBlock::removePositionedObject(*this);
 }

 void RenderBox::styleWillChange(StyleDifference diff, const RenderStyle& newStyle)
 {
     s_hadOverflowClip = hasOverflowClip();

     const RenderStyle* oldStyle = hasInitializedStyle() ? &style() : nullptr;
     if (oldStyle) {
         // The background of the root element or the body element could propagate up to
         // the canvas. Issue full repaint, when our style changes substantially.
         if (diff >= StyleDifference::Repaint && (isDocumentElementRenderer() || isBody())) {
             view().repaintRootContents();
             if (oldStyle->hasEntirelyFixedBackground() != newStyle.hasEntirelyFixedBackground())
                 view().compositor().rootLayerConfigurationChanged();
         }

         // When a layout hint happens and an object's position style changes, we have to do a layout
         // to dirty the render tree using the old position value now.
         if (diff == StyleDifference::Layout && parent() && oldStyle->position() != newStyle.position()) {
             markContainingBlocksForLayout();
             if (oldStyle->position() == PositionType::Static)
                 repaint();
             else if (newStyle.hasOutOfFlowPosition())
                 parent()->setChildNeedsLayout();
             if (isFloating() && !isOutOfFlowPositioned() && newStyle.hasOutOfFlowPosition())
                 removeFloatingOrPositionedChildFromBlockLists();
         }
     } else if (isBody())
         view().repaintRootContents();

 #if ENABLE(CSS_SCROLL_SNAP)
     bool boxContributesSnapPositions = newStyle.scrollSnapArea().hasSnapPosition();
     if (boxContributesSnapPositions || (oldStyle && oldStyle->scrollSnapArea().hasSnapPosition())) {
         if (boxContributesSnapPositions)
             view().registerBoxWithScrollSnapPositions(*this);
         else
             view().unregisterBoxWithScrollSnapPositions(*this);
     }
 #endif

     RenderBoxModelObject::styleWillChange(diff, newStyle);
 }

 void RenderBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
     // Horizontal writing mode definition is updated in RenderBoxModelObject::updateFromStyle,
     // (as part of the RenderBoxModelObject::styleDidChange call below). So, we can safely cache the horizontal
     // writing mode value before style change here.
     bool oldHorizontalWritingMode = isHorizontalWritingMode();

     RenderBoxModelObject::styleDidChange(diff, oldStyle);

     const RenderStyle& newStyle = style();
     if (needsLayout() && oldStyle) {
         RenderBlock::removePercentHeightDescendantIfNeeded(*this);

         // Normally we can do optimized positioning layout for absolute/fixed positioned objects. There is one special case, however, which is
         // when the positioned object's margin-before is changed. In this case the parent has to get a layout in order to run margin collapsing
         // to determine the new static position.
         if (isOutOfFlowPositioned() && newStyle.hasStaticBlockPosition(isHorizontalWritingMode()) && oldStyle->marginBefore() != newStyle.marginBefore()
             && parent() && !parent()->normalChildNeedsLayout())
             parent()->setChildNeedsLayout();
     }

     if (RenderBlock::hasPercentHeightContainerMap() && firstChild()
         && oldHorizontalWritingMode != isHorizontalWritingMode())
         RenderBlock::clearPercentHeightDescendantsFrom(*this);

     // If our zoom factor changes and we have a defined scrollLeft/Top, we need to adjust that value into the
     // new zoomed coordinate space.
     if (hasOverflowClip() && layer() && oldStyle && oldStyle->effectiveZoom() != newStyle.effectiveZoom()) {
         ScrollPosition scrollPosition = layer()->scrollPosition();
         float zoomScaleFactor = newStyle.effectiveZoom() / oldStyle->effectiveZoom();
         scrollPosition.scale(zoomScaleFactor);
         layer()->setPostLayoutScrollPosition(scrollPosition);
     }

     // Our opaqueness might have changed without triggering layout.
     if (diff >= StyleDifference::Repaint && diff <= StyleDifference::RepaintLayer) {
         auto parentToInvalidate = parent();
         for (unsigned i = 0; i < backgroundObscurationTestMaxDepth && parentToInvalidate; ++i) {
             parentToInvalidate->invalidateBackgroundObscurationStatus();
             parentToInvalidate = parentToInvalidate->parent();
         }
     }

     bool isBodyRenderer = isBody();
     bool isDocElementRenderer = isDocumentElementRenderer();

     if (isDocElementRenderer || isBodyRenderer) {
         // Propagate the new writing mode and direction up to the RenderView.
         auto* documentElementRenderer = document().documentElement()->renderer();
         auto& viewStyle = view().mutableStyle();
         bool rootStyleChanged = false;
         bool viewDirectionOrWritingModeChanged = false;
         auto* rootRenderer = isBodyRenderer ? documentElementRenderer : nullptr;
         if (viewStyle.direction() != newStyle.direction() && (isDocElementRenderer || !documentElementRenderer->style().hasExplicitlySetDirection())) {
             viewStyle.setDirection(newStyle.direction());
             viewDirectionOrWritingModeChanged = true;
             if (isBodyRenderer) {
                 rootRenderer->mutableStyle().setDirection(newStyle.direction());
                 rootStyleChanged = true;
             }
             setNeedsLayoutAndPrefWidthsRecalc();

             view().frameView().topContentDirectionDidChange();
         }

         if (viewStyle.writingMode() != newStyle.writingMode() && (isDocElementRenderer || !documentElementRenderer->style().hasExplicitlySetWritingMode())) {
             viewStyle.setWritingMode(newStyle.writingMode());
             viewDirectionOrWritingModeChanged = true;
             view().setHorizontalWritingMode(newStyle.isHorizontalWritingMode());
             view().markAllDescendantsWithFloatsForLayout();
             if (isBodyRenderer) {
                 rootStyleChanged = true;
                 rootRenderer->mutableStyle().setWritingMode(newStyle.writingMode());
                 rootRenderer->setHorizontalWritingMode(newStyle.isHorizontalWritingMode());
             }
             setNeedsLayoutAndPrefWidthsRecalc();
         }

 #if ENABLE(DARK_MODE_CSS)
         view().frameView().recalculateBaseBackgroundColor();
 #endif

         view().frameView().recalculateScrollbarOverlayStyle();

         const Pagination& pagination = view().frameView().pagination();
         if (viewDirectionOrWritingModeChanged && pagination.mode != Pagination::Unpaginated) {
             viewStyle.setColumnStylesFromPaginationMode(pagination.mode);
             if (view().multiColumnFlow())
                 view().updateColumnProgressionFromStyle(viewStyle);
         }

         if (viewDirectionOrWritingModeChanged && view().multiColumnFlow())
             view().updateStylesForColumnChildren();

         if (rootStyleChanged && is<RenderBlockFlow>(rootRenderer) && downcast<RenderBlockFlow>(*rootRenderer).multiColumnFlow())
             downcast<RenderBlockFlow>(*rootRenderer).updateStylesForColumnChildren();

         if (isBodyRenderer && pagination.mode != Pagination::Unpaginated && page().paginationLineGridEnabled()) {
             // Propagate the body font back up to the RenderView and use it as
             // the basis of the grid.
             if (newStyle.fontDescription() != view().style().fontDescription()) {
                 view().mutableStyle().setFontDescription(FontCascadeDescription { newStyle.fontDescription() });
                 view().mutableStyle().fontCascade().update(&document().fontSelector());
             }
         }

         if (diff != StyleDifference::Equal)
             view().compositor().rootOrBodyStyleChanged(*this, oldStyle);
     }

     if ((oldStyle && oldStyle->shapeOutside()) || style().shapeOutside())
         updateShapeOutsideInfoAfterStyleChange(style(), oldStyle);
     updateGridPositionAfterStyleChange(style(), oldStyle);
 }

 void RenderBox::updateGridPositionAfterStyleChange(const RenderStyle& style, const RenderStyle* oldStyle)
 {
     if (!oldStyle || !is<RenderGrid>(parent()))
         return;

     if (oldStyle->gridItemColumnStart() == style.gridItemColumnStart()
         && oldStyle->gridItemColumnEnd() == style.gridItemColumnEnd()
         && oldStyle->gridItemRowStart() == style.gridItemRowStart()
         && oldStyle->gridItemRowEnd() == style.gridItemRowEnd()
         && oldStyle->order() == style.order()
         && oldStyle->hasOutOfFlowPosition() == style.hasOutOfFlowPosition())
         return;

     // Positioned items don't participate on the layout of the grid,
     // so we don't need to mark the grid as dirty if they change positions.
     if (oldStyle->hasOutOfFlowPosition() && style.hasOutOfFlowPosition())
         return;

     // It should be possible to not dirty the grid in some cases (like moving an
     // explicitly placed grid item).
     // For now, it's more simple to just always recompute the grid.
     downcast<RenderGrid>(*parent()).dirtyGrid();
 }

 void RenderBox::updateShapeOutsideInfoAfterStyleChange(const RenderStyle& style, const RenderStyle* oldStyle)
 {
     const ShapeValue* shapeOutside = style.shapeOutside();
     const ShapeValue* oldShapeOutside = oldStyle ? oldStyle->shapeOutside() : nullptr;

     Length shapeMargin = style.shapeMargin();
     Length oldShapeMargin = oldStyle ? oldStyle->shapeMargin() : RenderStyle::initialShapeMargin();

     float shapeImageThreshold = style.shapeImageThreshold();
     float oldShapeImageThreshold = oldStyle ? oldStyle->shapeImageThreshold() : RenderStyle::initialShapeImageThreshold();

     // FIXME: A future optimization would do a deep comparison for equality. (bug 100811)
     if (shapeOutside == oldShapeOutside && shapeMargin == oldShapeMargin && shapeImageThreshold == oldShapeImageThreshold)
         return;

     if (!shapeOutside)
         ShapeOutsideInfo::removeInfo(*this);
     else
         ShapeOutsideInfo::ensureInfo(*this).markShapeAsDirty();

     if (shapeOutside || shapeOutside != oldShapeOutside)
         markShapeOutsideDependentsForLayout();
 }

 void RenderBox::updateFromStyle()
 {
     RenderBoxModelObject::updateFromStyle();

     const RenderStyle& styleToUse = style();
     bool isDocElementRenderer = isDocumentElementRenderer();
     bool isViewObject = isRenderView();

     // The root and the RenderView always paint their backgrounds/borders.
     if (isDocElementRenderer || isViewObject)
         setHasVisibleBoxDecorations(true);

     setFloating(!isOutOfFlowPositioned() && styleToUse.isFloating());

     // We also handle <body> and <html>, whose overflow applies to the viewport.
     if (styleToUse.overflowX() != Overflow::Visible && !isDocElementRenderer && isRenderBlock()) {
         bool boxHasOverflowClip = true;
         if (isBody()) {
             // Overflow on the body can propagate to the viewport under the following conditions.
             // (1) The root element is <html>.
             // (2) We are the primary <body> (can be checked by looking at document.body).
             // (3) The root element has visible overflow.
             if (is<HTMLHtmlElement>(*document().documentElement())
                 && document().body() == element()
                 && document().documentElement()->renderer()->style().overflowX() == Overflow::Visible) {
                 boxHasOverflowClip = false;
             }
         }
         // Check for overflow clip.
         // It's sufficient to just check one direction, since it's illegal to have visible on only one overflow value.
         if (boxHasOverflowClip) {
             if (!s_hadOverflowClip && hasRenderOverflow()) {
                 // Erase the overflow.
                 // Overflow changes have to result in immediate repaints of the entire layout overflow area because
                 // repaints issued by removal of descendants get clipped using the updated style when they shouldn't.
                 repaintRectangle(visualOverflowRect());
                 repaintRectangle(layoutOverflowRect());
             }
             setHasOverflowClip();
         }
     }
     setHasTransformRelatedProperty(styleToUse.hasTransformRelatedProperty());
     setHasReflection(styleToUse.boxReflect());
 }

 void RenderBox::layout()
 {
     StackStats::LayoutCheckPoint layoutCheckPoint;
     ASSERT(needsLayout());

     RenderObject* child = firstChild();
     if (!child) {
         clearNeedsLayout();
         return;
     }

     LayoutStateMaintainer statePusher(*this, locationOffset(), style().isFlippedBlocksWritingMode());
     while (child) {
         if (child->needsLayout())
             downcast<RenderElement>(*child).layout();
         ASSERT(!child->needsLayout());
         child = child->nextSibling();
     }
     invalidateBackgroundObscurationStatus();
     clearNeedsLayout();
 }

 // More IE extensions.  clientWidth and clientHeight represent the interior of an object
 // excluding border and scrollbar.
 LayoutUnit RenderBox::clientWidth() const
 {
     return paddingBoxWidth();
 }

 LayoutUnit RenderBox::clientHeight() const
 {
     return paddingBoxHeight();
 }

 int RenderBox::scrollWidth() const
 {
     if (hasOverflowClip() && layer())
         return layer()->scrollWidth();
     // For objects with visible overflow, this matches IE.
     // FIXME: Need to work right with writing modes.
     if (style().isLeftToRightDirection()) {
         // FIXME: This should use snappedIntSize() instead with absolute coordinates.
         return roundToInt(std::max(clientWidth(), layoutOverflowRect().maxX() - borderLeft()));
     }
     return roundToInt(clientWidth() - std::min<LayoutUnit>(0, layoutOverflowRect().x() - borderLeft()));
 }

 int RenderBox::scrollHeight() const
 {
     if (hasOverflowClip() && layer())
         return layer()->scrollHeight();
     // For objects with visible overflow, this matches IE.
     // FIXME: Need to work right with writing modes.
     // FIXME: This should use snappedIntSize() instead with absolute coordinates.
     return roundToInt(std::max(clientHeight(), layoutOverflowRect().maxY() - borderTop()));
 }

 int RenderBox::scrollLeft() const
 {
     return hasOverflowClip() && layer() ? layer()->scrollPosition().x() : 0;
 }

 int RenderBox::scrollTop() const
 {
     return hasOverflowClip() && layer() ? layer()->scrollPosition().y() : 0;
 }

 static void setupWheelEventMonitor(RenderLayer& layer)
 {
     Page& page = layer.renderer().page();
     if (!page.isMonitoringWheelEvents())
         return;
     layer.scrollAnimator().setWheelEventTestMonitor(page.wheelEventTestMonitor());
 }

 void RenderBox::setScrollLeft(int newLeft, ScrollType scrollType, ScrollClamping clamping)
 {
     if (!hasOverflowClip() || !layer())
         return;
     setupWheelEventMonitor(*layer());
     layer()->scrollToXPosition(newLeft, scrollType, clamping);
 }

 void RenderBox::setScrollTop(int newTop, ScrollType scrollType, ScrollClamping clamping)
 {
     if (!hasOverflowClip() || !layer())
         return;
     setupWheelEventMonitor(*layer());
     layer()->scrollToYPosition(newTop, scrollType, clamping);
 }

 void RenderBox::absoluteRects(Vector<IntRect>& rects, const LayoutPoint& accumulatedOffset) const
 {
     rects.append(snappedIntRect(accumulatedOffset, size()));
 }

 void RenderBox::absoluteQuads(Vector<FloatQuad>& quads, bool* wasFixed) const
 {
     FloatRect localRect(0, 0, width(), height());

     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (fragmentedFlow && fragmentedFlow->absoluteQuadsForBox(quads, wasFixed, this, localRect.y(), localRect.maxY()))
         return;

     quads.append(localToAbsoluteQuad(localRect, UseTransforms, wasFixed));
 }

 void RenderBox::updateLayerTransform()
 {
     // Transform-origin depends on box size, so we need to update the layer transform after layout.
     if (hasLayer())
         layer()->updateTransform();
 }

 LayoutUnit RenderBox::constrainLogicalWidthInFragmentByMinMax(LayoutUnit logicalWidth, LayoutUnit availableWidth, RenderBlock& cb, RenderFragmentContainer* fragment) const
 {
     const RenderStyle& styleToUse = style();
     if (!styleToUse.logicalMaxWidth().isUndefined())
         logicalWidth = std::min(logicalWidth, computeLogicalWidthInFragmentUsing(MaxSize, styleToUse.logicalMaxWidth(), availableWidth, cb, fragment));
     return std::max(logicalWidth, computeLogicalWidthInFragmentUsing(MinSize, styleToUse.logicalMinWidth(), availableWidth, cb, fragment));
 }

 LayoutUnit RenderBox::constrainLogicalHeightByMinMax(LayoutUnit logicalHeight, Optional<LayoutUnit> intrinsicContentHeight) const
 {
     const RenderStyle& styleToUse = style();
     if (!styleToUse.logicalMaxHeight().isUndefined()) {
         if (Optional<LayoutUnit> maxH = computeLogicalHeightUsing(MaxSize, styleToUse.logicalMaxHeight(), intrinsicContentHeight))
             logicalHeight = std::min(logicalHeight, maxH.value());
     }
     if (Optional<LayoutUnit> computedLogicalHeight = computeLogicalHeightUsing(MinSize, styleToUse.logicalMinHeight(), intrinsicContentHeight))
         return std::max(logicalHeight, computedLogicalHeight.value());
     return logicalHeight;
 }

 LayoutUnit RenderBox::constrainContentBoxLogicalHeightByMinMax(LayoutUnit logicalHeight, Optional<LayoutUnit> intrinsicContentHeight) const
 {
     const RenderStyle& styleToUse = style();
     if (!styleToUse.logicalMaxHeight().isUndefined()) {
         if (Optional<LayoutUnit> maxH = computeContentLogicalHeight(MaxSize, styleToUse.logicalMaxHeight(), intrinsicContentHeight))
             logicalHeight = std::min(logicalHeight, maxH.value());
     }
     if (Optional<LayoutUnit> computedContentLogicalHeight = computeContentLogicalHeight(MinSize, styleToUse.logicalMinHeight(), intrinsicContentHeight))
         return std::max(logicalHeight, computedContentLogicalHeight.value());
     return logicalHeight;
 }

 RoundedRect::Radii RenderBox::borderRadii() const
 {
     auto& style = this->style();
     LayoutRect bounds = frameRect();

     unsigned borderLeft = style.borderLeftWidth();
     unsigned borderTop = style.borderTopWidth();
     bounds.moveBy(LayoutPoint(borderLeft, borderTop));
     bounds.contract(borderLeft + style.borderRightWidth(), borderTop + style.borderBottomWidth());
     return style.getRoundedBorderFor(bounds).radii();
 }

 LayoutRect RenderBox::paddingBoxRect() const
 {
     auto verticalScrollbarWidth = this->verticalScrollbarWidth();
     LayoutUnit offsetForScrollbar = shouldPlaceBlockDirectionScrollbarOnLeft() ? verticalScrollbarWidth : 0;

     return LayoutRect(borderLeft() + offsetForScrollbar, borderTop(),
         width() - borderLeft() - borderRight() - verticalScrollbarWidth,
         height() - borderTop() - borderBottom() - horizontalScrollbarHeight());
 }

 LayoutRect RenderBox::contentBoxRect() const
 {
     return { contentBoxLocation(), contentSize() };
 }

 LayoutPoint RenderBox::contentBoxLocation() const
 {
     LayoutUnit scrollbarSpace = shouldPlaceBlockDirectionScrollbarOnLeft() ? verticalScrollbarWidth() : 0;
     return { borderLeft() + paddingLeft() + scrollbarSpace, borderTop() + paddingTop() };
 }

 IntRect RenderBox::absoluteContentBox() const
 {
     // This is wrong with transforms and flipped writing modes.
     IntRect rect = snappedIntRect(contentBoxRect());
     FloatPoint absPos = localToAbsolute();
     rect.move(absPos.x(), absPos.y());
     return rect;
 }

 FloatQuad RenderBox::absoluteContentQuad() const
 {
     LayoutRect rect = contentBoxRect();
     return localToAbsoluteQuad(FloatRect(rect));
 }

 LayoutRect RenderBox::outlineBoundsForRepaint(const RenderLayerModelObject* repaintContainer, const RenderGeometryMap* geometryMap) const
 {
     LayoutRect box = borderBoundingBox();
     adjustRectForOutlineAndShadow(box);

     if (repaintContainer != this) {
         FloatQuad containerRelativeQuad;
         if (geometryMap)
             containerRelativeQuad = geometryMap->mapToContainer(box, repaintContainer);
         else
             containerRelativeQuad = localToContainerQuad(FloatRect(box), repaintContainer);

         box = LayoutRect(containerRelativeQuad.boundingBox());
     }

     // FIXME: layoutDelta needs to be applied in parts before/after transforms and
     // repaint containers. https://bugs.webkit.org/show_bug.cgi?id=23308
     box.move(view().frameView().layoutContext().layoutDelta());

     return LayoutRect(snapRectToDevicePixels(box, document().deviceScaleFactor()));
 }

 void RenderBox::addFocusRingRects(Vector<LayoutRect>& rects, const LayoutPoint& additionalOffset, const RenderLayerModelObject*)
 {
     if (!size().isEmpty())
         rects.append(LayoutRect(additionalOffset, size()));
 }

 int RenderBox::reflectionOffset() const
 {
     if (!style().boxReflect())
         return 0;
     if (style().boxReflect()->direction() == ReflectionDirection::Left || style().boxReflect()->direction() == ReflectionDirection::Right)
         return valueForLength(style().boxReflect()->offset(), borderBoxRect().width());
     return valueForLength(style().boxReflect()->offset(), borderBoxRect().height());
 }

 LayoutRect RenderBox::reflectedRect(const LayoutRect& r) const
 {
     if (!style().boxReflect())
         return LayoutRect();

     LayoutRect box = borderBoxRect();
     LayoutRect result = r;
     switch (style().boxReflect()->direction()) {
     case ReflectionDirection::Below:
         result.setY(box.maxY() + reflectionOffset() + (box.maxY() - r.maxY()));
         break;
     case ReflectionDirection::Above:
         result.setY(box.y() - reflectionOffset() - box.height() + (box.maxY() - r.maxY()));
         break;
     case ReflectionDirection::Left:
         result.setX(box.x() - reflectionOffset() - box.width() + (box.maxX() - r.maxX()));
         break;
     case ReflectionDirection::Right:
         result.setX(box.maxX() + reflectionOffset() + (box.maxX() - r.maxX()));
         break;
     }
     return result;
 }

 bool RenderBox::fixedElementLaysOutRelativeToFrame(const FrameView& frameView) const
 {
     return isFixedPositioned() && container()->isRenderView() && frameView.fixedElementsLayoutRelativeToFrame();
 }

 bool RenderBox::includeVerticalScrollbarSize() const
 {
     return hasOverflowClip() && layer() && !layer()->hasOverlayScrollbars()
         && (style().overflowY() == Overflow::Scroll || style().overflowY() == Overflow::Auto);
 }

 bool RenderBox::includeHorizontalScrollbarSize() const
 {
     return hasOverflowClip() && layer() && !layer()->hasOverlayScrollbars()
         && (style().overflowX() == Overflow::Scroll || style().overflowX() == Overflow::Auto);
 }

 int RenderBox::verticalScrollbarWidth() const
 {
     return includeVerticalScrollbarSize() ? layer()->verticalScrollbarWidth() : 0;
 }

 int RenderBox::horizontalScrollbarHeight() const
 {
     return includeHorizontalScrollbarSize() ? layer()->horizontalScrollbarHeight() : 0;
 }

 int RenderBox::intrinsicScrollbarLogicalWidth() const
 {
     if (!hasOverflowClip())
         return 0;

     if (isHorizontalWritingMode() && (style().overflowY() == Overflow::Scroll && !canUseOverlayScrollbars())) {
         ASSERT(layer() && layer()->hasVerticalScrollbar());
         return verticalScrollbarWidth();
     }

     if (!isHorizontalWritingMode() && (style().overflowX() == Overflow::Scroll && !canUseOverlayScrollbars())) {
         ASSERT(layer() && layer()->hasHorizontalScrollbar());
         return horizontalScrollbarHeight();
     }

     return 0;
 }

 bool RenderBox::scrollLayer(ScrollDirection direction, ScrollGranularity granularity, float multiplier, Element** stopElement)
 {
     RenderLayer* boxLayer = layer();
     if (boxLayer && boxLayer->scroll(direction, granularity, multiplier)) {
         if (stopElement)
             *stopElement = element();

         return true;
     }

     return false;
 }

 bool RenderBox::scroll(ScrollDirection direction, ScrollGranularity granularity, float multiplier, Element** stopElement, RenderBox* startBox, const IntPoint& wheelEventAbsolutePoint)
 {
     if (scrollLayer(direction, granularity, multiplier, stopElement))
         return true;

     if (stopElement && *stopElement && *stopElement == element())
         return true;

     RenderBlock* nextScrollBlock = containingBlock();

     if (nextScrollBlock && !nextScrollBlock->isRenderView())
         return nextScrollBlock->scroll(direction, granularity, multiplier, stopElement, startBox, wheelEventAbsolutePoint);

     return false;
 }

 bool RenderBox::logicalScroll(ScrollLogicalDirection direction, ScrollGranularity granularity, float multiplier, Element** stopElement)
 {
     bool scrolled = false;

     RenderLayer* l = layer();
     if (l) {
 #if PLATFORM(COCOA)
         // On Mac only we reset the inline direction position when doing a document scroll (e.g., hitting Home/End).
         if (granularity == ScrollByDocument)
             scrolled = l->scroll(logicalToPhysical(ScrollInlineDirectionBackward, isHorizontalWritingMode(), style().isFlippedBlocksWritingMode()), ScrollByDocument, multiplier);
 #endif
         if (l->scroll(logicalToPhysical(direction, isHorizontalWritingMode(), style().isFlippedBlocksWritingMode()), granularity, multiplier))
             scrolled = true;

         if (scrolled) {
             if (stopElement)
                 *stopElement = element();
             return true;
         }
     }

     if (stopElement && *stopElement && *stopElement == element())
         return true;

     RenderBlock* b = containingBlock();
     if (b && !b->isRenderView())
         return b->logicalScroll(direction, granularity, multiplier, stopElement);
     return false;
 }

 bool RenderBox::canBeScrolledAndHasScrollableArea() const
 {
     return canBeProgramaticallyScrolled() && (hasHorizontalOverflow() || hasVerticalOverflow());
 }

 bool RenderBox::isScrollableOrRubberbandableBox() const
 {
     return canBeScrolledAndHasScrollableArea();
 }

 // FIXME: This is badly named. overflow:hidden can be programmatically scrolled, yet this returns false in that case.
 bool RenderBox::canBeProgramaticallyScrolled() const
 {
     if (isRenderView())
         return true;

     if (!hasOverflowClip())
         return false;

     if (hasScrollableOverflowX() || hasScrollableOverflowY())
         return true;

     return element() && element()->hasEditableStyle();
 }

 bool RenderBox::usesCompositedScrolling() const
 {
     return hasOverflowClip() && hasLayer() && layer()->usesCompositedScrolling();
 }

 void RenderBox::autoscroll(const IntPoint& position)
 {
     if (layer())
         layer()->autoscroll(position);
 }

 // There are two kinds of renderer that can autoscroll.
 bool RenderBox::canAutoscroll() const
 {
     if (isRenderView())
         return view().frameView().isScrollable();

     // Check for a box that can be scrolled in its own right.
     if (canBeScrolledAndHasScrollableArea())
         return true;

     return false;
 }

 // If specified point is in border belt, returned offset denotes direction of
 // scrolling.
 IntSize RenderBox::calculateAutoscrollDirection(const IntPoint& windowPoint) const
 {
     IntRect box(absoluteBoundingBoxRect());
     box.moveBy(view().frameView().scrollPosition());
     IntRect windowBox = view().frameView().contentsToWindow(box);

     IntPoint windowAutoscrollPoint = windowPoint;

     if (windowAutoscrollPoint.x() < windowBox.x() + autoscrollBeltSize)
         windowAutoscrollPoint.move(-autoscrollBeltSize, 0);
     else if (windowAutoscrollPoint.x() > windowBox.maxX() - autoscrollBeltSize)
         windowAutoscrollPoint.move(autoscrollBeltSize, 0);

     if (windowAutoscrollPoint.y() < windowBox.y() + autoscrollBeltSize)
         windowAutoscrollPoint.move(0, -autoscrollBeltSize);
     else if (windowAutoscrollPoint.y() > windowBox.maxY() - autoscrollBeltSize)
         windowAutoscrollPoint.move(0, autoscrollBeltSize);

     return windowAutoscrollPoint - windowPoint;
 }

 RenderBox* RenderBox::findAutoscrollable(RenderObject* renderer)
 {
     while (renderer && !(is<RenderBox>(*renderer) && downcast<RenderBox>(*renderer).canAutoscroll())) {
         if (is<RenderView>(*renderer) && renderer->document().ownerElement())
             renderer = renderer->document().ownerElement()->renderer();
         else
             renderer = renderer->parent();
     }

     return is<RenderBox>(renderer) ? downcast<RenderBox>(renderer) : nullptr;
 }

 void RenderBox::panScroll(const IntPoint& source)
 {
     if (layer())
         layer()->panScrollFromPoint(source);
 }

 bool RenderBox::canUseOverlayScrollbars() const
 {
     return !style().hasPseudoStyle(PseudoId::Scrollbar) && ScrollbarTheme::theme().usesOverlayScrollbars();
 }

 bool RenderBox::hasVerticalScrollbarWithAutoBehavior() const
 {
     return hasOverflowClip() && (style().overflowY() == Overflow::Auto || (style().overflowY() == Overflow::Scroll && canUseOverlayScrollbars()));
 }

 bool RenderBox::hasHorizontalScrollbarWithAutoBehavior() const
 {
     return hasOverflowClip() && (style().overflowX() == Overflow::Auto || (style().overflowX() == Overflow::Scroll && canUseOverlayScrollbars()));
 }

 bool RenderBox::needsPreferredWidthsRecalculation() const
 {
     return style().paddingStart().isPercentOrCalculated() || style().paddingEnd().isPercentOrCalculated();
 }

 ScrollPosition RenderBox::scrollPosition() const
 {
     if (!hasOverflowClip())
         return { 0, 0 };

     ASSERT(hasLayer());
     return layer()->scrollPosition();
 }

 LayoutSize RenderBox::cachedSizeForOverflowClip() const
 {
     ASSERT(hasOverflowClip());
     ASSERT(hasLayer());
     return layer()->size();
 }

 bool RenderBox::applyCachedClipAndScrollPosition(LayoutRect& rect, const RenderLayerModelObject* container, VisibleRectContext context) const
 {
     flipForWritingMode(rect);

     if (context.m_options.contains(VisibleRectContextOption::ApplyCompositedContainerScrolls) || this != container || !usesCompositedScrolling())
         rect.moveBy(-scrollPosition()); // For overflow:auto/scroll/hidden.

     // Do not clip scroll layer contents to reduce the number of repaints while scrolling.
     if ((!context.m_options.contains(VisibleRectContextOption::ApplyCompositedClips) && usesCompositedScrolling())
         || (!context.m_options.contains(VisibleRectContextOption::ApplyContainerClip) && this == container)) {
         flipForWritingMode(rect);
         return true;
     }

     // height() is inaccurate if we're in the middle of a layout of this RenderBox, so use the
     // layer's size instead. Even if the layer's size is wrong, the layer itself will repaint
     // anyway if its size does change.
     LayoutRect clipRect(LayoutPoint(), cachedSizeForOverflowClip());
     bool intersects;
     if (context.m_options.contains(VisibleRectContextOption::UseEdgeInclusiveIntersection))
         intersects = rect.edgeInclusiveIntersect(clipRect);
     else {
         rect.intersect(clipRect);
         intersects = !rect.isEmpty();
     }
     flipForWritingMode(rect);
     return intersects;
 }

 void RenderBox::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 {
     minLogicalWidth = minPreferredLogicalWidth() - borderAndPaddingLogicalWidth();
     maxLogicalWidth = maxPreferredLogicalWidth() - borderAndPaddingLogicalWidth();
 }

 LayoutUnit RenderBox::minPreferredLogicalWidth() const
 {
     if (preferredLogicalWidthsDirty()) {
 #ifndef NDEBUG
         SetLayoutNeededForbiddenScope layoutForbiddenScope(const_cast<RenderBox*>(this));
 #endif
         const_cast<RenderBox*>(this)->computePreferredLogicalWidths();
     }

     return m_minPreferredLogicalWidth;
 }

 LayoutUnit RenderBox::maxPreferredLogicalWidth() const
 {
     if (preferredLogicalWidthsDirty()) {
 #ifndef NDEBUG
         SetLayoutNeededForbiddenScope layoutForbiddenScope(const_cast<RenderBox*>(this));
 #endif
         const_cast<RenderBox*>(this)->computePreferredLogicalWidths();
     }

     return m_maxPreferredLogicalWidth;
 }

 bool RenderBox::hasOverrideContentLogicalHeight() const
 {
     return gOverrideContentLogicalHeightMap && gOverrideContentLogicalHeightMap->contains(this);
 }

 bool RenderBox::hasOverrideContentLogicalWidth() const
 {
     return gOverrideContentLogicalWidthMap && gOverrideContentLogicalWidthMap->contains(this);
 }

 void RenderBox::setOverrideContentLogicalHeight(LayoutUnit height)
 {
     if (!gOverrideContentLogicalHeightMap)
         gOverrideContentLogicalHeightMap = new OverrideSizeMap();
     gOverrideContentLogicalHeightMap->set(this, height);
 }

 void RenderBox::setOverrideContentLogicalWidth(LayoutUnit width)
 {
     if (!gOverrideContentLogicalWidthMap)
         gOverrideContentLogicalWidthMap = new OverrideSizeMap();
     gOverrideContentLogicalWidthMap->set(this, width);
 }

 void RenderBox::clearOverrideContentLogicalHeight()
 {
     if (gOverrideContentLogicalHeightMap)
         gOverrideContentLogicalHeightMap->remove(this);
 }

 void RenderBox::clearOverrideContentLogicalWidth()
 {
     if (gOverrideContentLogicalWidthMap)
         gOverrideContentLogicalWidthMap->remove(this);
 }

 void RenderBox::clearOverrideContentSize()
 {
     clearOverrideContentLogicalHeight();
     clearOverrideContentLogicalWidth();
 }

 LayoutUnit RenderBox::overrideContentLogicalWidth() const
 {
     ASSERT(hasOverrideContentLogicalWidth());
     return gOverrideContentLogicalWidthMap->get(this);
 }

 LayoutUnit RenderBox::overrideContentLogicalHeight() const
 {
     ASSERT(hasOverrideContentLogicalHeight());
     return gOverrideContentLogicalHeightMap->get(this);
 }

 Optional<LayoutUnit> RenderBox::overrideContainingBlockContentWidth() const
 {
     ASSERT(hasOverrideContainingBlockContentWidth());
     return containingBlock()->style().isHorizontalWritingMode()
         ? gOverrideContainingBlockContentLogicalWidthMap->get(this)
         : gOverrideContainingBlockContentLogicalHeightMap->get(this);
 }

 Optional<LayoutUnit> RenderBox::overrideContainingBlockContentHeight() const
 {
     ASSERT(hasOverrideContainingBlockContentHeight());
     return containingBlock()->style().isHorizontalWritingMode()
         ? gOverrideContainingBlockContentLogicalHeightMap->get(this)
         : gOverrideContainingBlockContentLogicalWidthMap->get(this);
 }

 bool RenderBox::hasOverrideContainingBlockContentWidth() const
 {
     RenderBlock* cb = containingBlock();
     if (!cb)
         return false;

     return cb->style().isHorizontalWritingMode()
         ? gOverrideContainingBlockContentLogicalWidthMap && gOverrideContainingBlockContentLogicalWidthMap->contains(this)
         : gOverrideContainingBlockContentLogicalHeightMap && gOverrideContainingBlockContentLogicalHeightMap->contains(this);
 }

 bool RenderBox::hasOverrideContainingBlockContentHeight() const
 {
     RenderBlock* cb = containingBlock();
     if (!cb)
         return false;

     return cb->style().isHorizontalWritingMode()
         ? gOverrideContainingBlockContentLogicalHeightMap && gOverrideContainingBlockContentLogicalHeightMap->contains(this)
         : gOverrideContainingBlockContentLogicalHeightMap && gOverrideContainingBlockContentLogicalHeightMap->contains(this);
 }

 Optional<LayoutUnit> RenderBox::overrideContainingBlockContentLogicalWidth() const
 {
     ASSERT(hasOverrideContainingBlockContentLogicalWidth());
     return gOverrideContainingBlockContentLogicalWidthMap->get(this);
 }

 Optional<LayoutUnit> RenderBox::overrideContainingBlockContentLogicalHeight() const
 {
     ASSERT(hasOverrideContainingBlockContentLogicalHeight());
     return gOverrideContainingBlockContentLogicalHeightMap->get(this);
 }

 bool RenderBox::hasOverrideContainingBlockContentLogicalWidth() const
 {
     return gOverrideContainingBlockContentLogicalWidthMap && gOverrideContainingBlockContentLogicalWidthMap->contains(this);
 }

 bool RenderBox::hasOverrideContainingBlockContentLogicalHeight() const
 {
     return gOverrideContainingBlockContentLogicalHeightMap && gOverrideContainingBlockContentLogicalHeightMap->contains(this);
 }

 void RenderBox::setOverrideContainingBlockContentLogicalWidth(Optional<LayoutUnit> logicalWidth)
 {
     if (!gOverrideContainingBlockContentLogicalWidthMap)
         gOverrideContainingBlockContentLogicalWidthMap = new OverrideOptionalSizeMap;
     gOverrideContainingBlockContentLogicalWidthMap->set(this, logicalWidth);
 }

 void RenderBox::setOverrideContainingBlockContentLogicalHeight(Optional<LayoutUnit> logicalHeight)
 {
     if (!gOverrideContainingBlockContentLogicalHeightMap)
         gOverrideContainingBlockContentLogicalHeightMap = new OverrideOptionalSizeMap;
     gOverrideContainingBlockContentLogicalHeightMap->set(this, logicalHeight);
 }

 void RenderBox::clearOverrideContainingBlockContentSize()
 {
     if (gOverrideContainingBlockContentLogicalWidthMap)
         gOverrideContainingBlockContentLogicalWidthMap->remove(this);
     clearOverrideContainingBlockContentLogicalHeight();
 }

 void RenderBox::clearOverrideContainingBlockContentLogicalHeight()
 {
     if (gOverrideContainingBlockContentLogicalHeightMap)
         gOverrideContainingBlockContentLogicalHeightMap->remove(this);
 }

 LayoutUnit RenderBox::adjustBorderBoxLogicalWidthForBoxSizing(LayoutUnit width) const
 {
     LayoutUnit bordersPlusPadding = borderAndPaddingLogicalWidth();
     if (style().boxSizing() == BoxSizing::ContentBox)
         return width + bordersPlusPadding;
     return std::max(width, bordersPlusPadding);
 }

 LayoutUnit RenderBox::adjustBorderBoxLogicalHeightForBoxSizing(LayoutUnit height) const
 {
     LayoutUnit bordersPlusPadding = borderAndPaddingLogicalHeight();
     if (style().boxSizing() == BoxSizing::ContentBox)
         return height + bordersPlusPadding;
     return std::max(height, bordersPlusPadding);
 }

 LayoutUnit RenderBox::adjustContentBoxLogicalWidthForBoxSizing(LayoutUnit width) const
 {
     if (style().boxSizing() == BoxSizing::BorderBox)
         width -= borderAndPaddingLogicalWidth();
     return std::max<LayoutUnit>(0, width);
 }

 LayoutUnit RenderBox::adjustContentBoxLogicalHeightForBoxSizing(Optional<LayoutUnit> height) const
 {
     if (!height)
         return 0;
     LayoutUnit result = height.value();
     if (style().boxSizing() == BoxSizing::BorderBox)
         result -= borderAndPaddingLogicalHeight();
     return std::max(0_lu, result);
 }

 // Hit Testing
 bool RenderBox::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction action)
 {
     LayoutPoint adjustedLocation = accumulatedOffset + location();

     // Check kids first.
     for (RenderObject* child = lastChild(); child; child = child->previousSibling()) {
         if (!child->hasLayer() && child->nodeAtPoint(request, result, locationInContainer, adjustedLocation, action)) {
             updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
             return true;
         }
     }

     // Check our bounds next. For this purpose always assume that we can only be hit in the
     // foreground phase (which is true for replaced elements like images).
     LayoutRect boundsRect = borderBoxRectInFragment(nullptr);
     boundsRect.moveBy(adjustedLocation);
     if (visibleToHitTesting() && action == HitTestForeground && locationInContainer.intersects(boundsRect)) {
         updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
         if (result.addNodeToListBasedTestResult(element(), request, locationInContainer, boundsRect) == HitTestProgress::Stop)
             return true;
     }

     return false;
 }

 // --------------------- painting stuff -------------------------------

 void RenderBox::paintRootBoxFillLayers(const PaintInfo& paintInfo)
 {
     ASSERT(isDocumentElementRenderer());
     if (paintInfo.skipRootBackground())
         return;

     auto* rootBackgroundRenderer = view().rendererForRootBackground();
     if (!rootBackgroundRenderer)
         return;

     auto& style = rootBackgroundRenderer->style();
     auto color = style.visitedDependentColor(CSSPropertyBackgroundColor);
     auto compositeOp = document().compositeOperatorForBackgroundColor(color, *this);

     paintFillLayers(paintInfo, style.colorByApplyingColorFilter(color), style.backgroundLayers(), view().backgroundRect(), BackgroundBleedNone, compositeOp, rootBackgroundRenderer);
 }

 BackgroundBleedAvoidance RenderBox::determineBackgroundBleedAvoidance(GraphicsContext& context) const
 {
     if (context.paintingDisabled())
         return BackgroundBleedNone;

     const RenderStyle& style = this->style();

     if (!style.hasBackground() || !style.hasBorder() || !style.hasBorderRadius() || borderImageIsLoadedAndCanBeRendered())
         return BackgroundBleedNone;

     AffineTransform ctm = context.getCTM();
     FloatSize contextScaling(static_cast<float>(ctm.xScale()), static_cast<float>(ctm.yScale()));

     // Because RoundedRect uses IntRect internally the inset applied by the
     // BackgroundBleedShrinkBackground strategy cannot be less than one integer
     // layout coordinate, even with subpixel layout enabled. To take that into
     // account, we clamp the contextScaling to 1.0 for the following test so
     // that borderObscuresBackgroundEdge can only return true if the border
     // widths are greater than 2 in both layout coordinates and screen
     // coordinates.
     // This precaution will become obsolete if RoundedRect is ever promoted to
     // a sub-pixel representation.
     if (contextScaling.width() > 1)
         contextScaling.setWidth(1);
     if (contextScaling.height() > 1)
         contextScaling.setHeight(1);

     if (borderObscuresBackgroundEdge(contextScaling))
         return BackgroundBleedShrinkBackground;
     if (!style.hasAppearance() && borderObscuresBackground() && backgroundHasOpaqueTopLayer())
         return BackgroundBleedBackgroundOverBorder;

     return BackgroundBleedUseTransparencyLayer;
 }

 void RenderBox::paintBoxDecorations(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (!paintInfo.shouldPaintWithinRoot(*this))
         return;

     LayoutRect paintRect = borderBoxRectInFragment(nullptr);
     paintRect.moveBy(paintOffset);
     adjustBorderBoxRectForPainting(paintRect);

 #if PLATFORM(IOS_FAMILY)
     // Workaround for <rdar://problem/6209763>. Force the painting bounds of checkboxes and radio controls to be square.
     // FIXME: Consolidate this code with the same code in RenderElement::paintOutline(). See <https://bugs.webkit.org/show_bug.cgi?id=194781>.
     if (style().appearance() == CheckboxPart || style().appearance() == RadioPart) {
         int width = std::min(paintRect.width(), paintRect.height());
         int height = width;
         paintRect = IntRect { paintRect.x(), paintRect.y() + (this->height() - height) / 2, width, height }; // Vertically center the checkbox, like on desktop
     }
 #endif
     BackgroundBleedAvoidance bleedAvoidance = determineBackgroundBleedAvoidance(paintInfo.context());

     // FIXME: Should eventually give the theme control over whether the box shadow should paint, since controls could have
     // custom shadows of their own.
     if (!boxShadowShouldBeAppliedToBackground(paintRect.location(), bleedAvoidance))
         paintBoxShadow(paintInfo, paintRect, style(), Normal);

     GraphicsContextStateSaver stateSaver(paintInfo.context(), false);
     if (bleedAvoidance == BackgroundBleedUseTransparencyLayer) {
         // To avoid the background color bleeding out behind the border, we'll render background and border
         // into a transparency layer, and then clip that in one go (which requires setting up the clip before
         // beginning the layer).
         stateSaver.save();
         paintInfo.context().clipRoundedRect(style().getRoundedBorderFor(paintRect).pixelSnappedRoundedRectForPainting(document().deviceScaleFactor()));
         paintInfo.context().beginTransparencyLayer(1);
     }

     // If we have a native theme appearance, paint that before painting our background.
     // The theme will tell us whether or not we should also paint the CSS background.
     bool borderOrBackgroundPaintingIsNeeded = true;
     if (style().hasAppearance()) {
         ControlStates* controlStates = controlStatesForRenderer(*this);
         borderOrBackgroundPaintingIsNeeded = theme().paint(*this, *controlStates, paintInfo, paintRect);
         if (controlStates->needsRepaint())
             view().scheduleLazyRepaint(*this);
     }

     if (borderOrBackgroundPaintingIsNeeded) {
         if (bleedAvoidance == BackgroundBleedBackgroundOverBorder)
             paintBorder(paintInfo, paintRect, style(), bleedAvoidance);

         paintBackground(paintInfo, paintRect, bleedAvoidance);

         if (style().hasAppearance())
             theme().paintDecorations(*this, paintInfo, paintRect);
     }
     paintBoxShadow(paintInfo, paintRect, style(), Inset);

     // The theme will tell us whether or not we should also paint the CSS border.
     if (bleedAvoidance != BackgroundBleedBackgroundOverBorder && (!style().hasAppearance() || (borderOrBackgroundPaintingIsNeeded && theme().paintBorderOnly(*this, paintInfo, paintRect))) && style().hasVisibleBorderDecoration())
         paintBorder(paintInfo, paintRect, style(), bleedAvoidance);

     if (bleedAvoidance == BackgroundBleedUseTransparencyLayer)
         paintInfo.context().endTransparencyLayer();
 }

 bool RenderBox::paintsOwnBackground() const
 {
     if (isBody()) {
         // The <body> only paints its background if the root element has defined a background independent of the body,
         // or if the <body>'s parent is not the document element's renderer (e.g. inside SVG foreignObject).
         auto documentElementRenderer = document().documentElement()->renderer();
         return !documentElementRenderer
             || documentElementRenderer->hasBackground()
             || (documentElementRenderer != parent());
     }

     return true;
 }

 void RenderBox::paintBackground(const PaintInfo& paintInfo, const LayoutRect& paintRect, BackgroundBleedAvoidance bleedAvoidance)
 {
     if (isDocumentElementRenderer()) {
         paintRootBoxFillLayers(paintInfo);
         return;
     }

     if (!paintsOwnBackground())
         return;

     if (backgroundIsKnownToBeObscured(paintRect.location()) && !boxShadowShouldBeAppliedToBackground(paintRect.location(), bleedAvoidance))
         return;

     auto backgroundColor = style().visitedDependentColor(CSSPropertyBackgroundColor);
     auto compositeOp = document().compositeOperatorForBackgroundColor(backgroundColor, *this);

     paintFillLayers(paintInfo, style().colorByApplyingColorFilter(backgroundColor), style().backgroundLayers(), paintRect, bleedAvoidance, compositeOp);
 }

 bool RenderBox::getBackgroundPaintedExtent(const LayoutPoint& paintOffset, LayoutRect& paintedExtent) const
 {
     ASSERT(hasBackground());
     LayoutRect backgroundRect = snappedIntRect(borderBoxRect());

     Color backgroundColor = style().visitedDependentColorWithColorFilter(CSSPropertyBackgroundColor);
     if (backgroundColor.isVisible()) {
         paintedExtent = backgroundRect;
         return true;
     }

     auto& layers = style().backgroundLayers();
     if (!layers.image() || layers.next()) {
         paintedExtent =  backgroundRect;
         return true;
     }

     auto geometry = calculateBackgroundImageGeometry(nullptr, layers, paintOffset, backgroundRect);
     paintedExtent = geometry.destRect();
     return !geometry.hasNonLocalGeometry();
 }

 bool RenderBox::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
 {
     if (!paintsOwnBackground())
         return false;

     Color backgroundColor = style().visitedDependentColorWithColorFilter(CSSPropertyBackgroundColor);
     if (!backgroundColor.isOpaque())
         return false;

     // If the element has appearance, it might be painted by theme.
     // We cannot be sure if theme paints the background opaque.
     // In this case it is safe to not assume opaqueness.
     // FIXME: May be ask theme if it paints opaque.
     if (style().hasAppearance())
         return false;
     // FIXME: Check the opaqueness of background images.

     if (hasClip() || hasClipPath())
         return false;

     // FIXME: Use rounded rect if border radius is present.
     if (style().hasBorderRadius())
         return false;

     // FIXME: The background color clip is defined by the last layer.
     if (style().backgroundLayers().next())
         return false;
     LayoutRect backgroundRect;
     switch (style().backgroundClip()) {
     case FillBox::Border:
         backgroundRect = borderBoxRect();
         break;
     case FillBox::Padding:
         backgroundRect = paddingBoxRect();
         break;
     case FillBox::Content:
         backgroundRect = contentBoxRect();
         break;
     default:
         break;
     }
     return backgroundRect.contains(localRect);
 }

 static bool isCandidateForOpaquenessTest(const RenderBox& childBox)
 {
     const RenderStyle& childStyle = childBox.style();
     if (childStyle.position() != PositionType::Static && childBox.containingBlock() != childBox.parent())
         return false;
     if (childStyle.visibility() != Visibility::Visible)
         return false;
     if (childStyle.shapeOutside())
         return false;
     if (!childBox.width() || !childBox.height())
         return false;
     if (RenderLayer* childLayer = childBox.layer()) {
         if (childLayer->isComposited())
             return false;
         // FIXME: Deal with z-index.
         if (!childStyle.hasAutoZIndex())
             return false;
         if (childLayer->hasTransform() || childLayer->isTransparent() || childLayer->hasFilter())
             return false;
         if (!childBox.scrollPosition().isZero())
             return false;
     }
     return true;
 }

 bool RenderBox::foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const
 {
     if (!maxDepthToTest)
         return false;

     for (auto& childBox : childrenOfType<RenderBox>(*this)) {
         if (!isCandidateForOpaquenessTest(childBox))
             continue;
         LayoutPoint childLocation = childBox.location();
         if (childBox.isRelativelyPositioned())
             childLocation.move(childBox.relativePositionOffset());
         LayoutRect childLocalRect = localRect;
         childLocalRect.moveBy(-childLocation);
         if (childLocalRect.y() < 0 || childLocalRect.x() < 0) {
             // If there is unobscured area above/left of a static positioned box then the rect is probably not covered.
             if (childBox.style().position() == PositionType::Static)
                 return false;
             continue;
         }
         if (childLocalRect.maxY() > childBox.height() || childLocalRect.maxX() > childBox.width())
             continue;
         if (childBox.backgroundIsKnownToBeOpaqueInRect(childLocalRect))
             return true;
         if (childBox.foregroundIsKnownToBeOpaqueInRect(childLocalRect, maxDepthToTest - 1))
             return true;
     }
     return false;
 }

 bool RenderBox::computeBackgroundIsKnownToBeObscured(const LayoutPoint& paintOffset)
 {
     // Test to see if the children trivially obscure the background.
     // FIXME: This test can be much more comprehensive.
     if (!hasBackground())
         return false;
     // Table and root background painting is special.
     if (isTable() || isDocumentElementRenderer())
         return false;

     LayoutRect backgroundRect;
     if (!getBackgroundPaintedExtent(paintOffset, backgroundRect))
         return false;

     if (hasLayer() && layer()->scrollingMayRevealBackground())
         return false;

     return foregroundIsKnownToBeOpaqueInRect(backgroundRect, backgroundObscurationTestMaxDepth);
 }

 bool RenderBox::backgroundHasOpaqueTopLayer() const
 {
     auto& fillLayer = style().backgroundLayers();
     if (fillLayer.clip() != FillBox::Border)
         return false;

     // Clipped with local scrolling
     if (hasOverflowClip() && fillLayer.attachment() == FillAttachment::LocalBackground)
         return false;

     if (fillLayer.hasOpaqueImage(*this) && fillLayer.hasRepeatXY() && fillLayer.image()->canRender(this, style().effectiveZoom()))
         return true;

     // If there is only one layer and no image, check whether the background color is opaque.
     if (!fillLayer.next() && !fillLayer.hasImage()) {
         Color bgColor = style().visitedDependentColorWithColorFilter(CSSPropertyBackgroundColor);
         if (bgColor.isOpaque())
             return true;
     }

     return false;
 }

 void RenderBox::paintMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (!paintInfo.shouldPaintWithinRoot(*this) || style().visibility() != Visibility::Visible || paintInfo.phase != PaintPhase::Mask || paintInfo.context().paintingDisabled())
         return;

     LayoutRect paintRect = LayoutRect(paintOffset, size());
     adjustBorderBoxRectForPainting(paintRect);
     paintMaskImages(paintInfo, paintRect);
 }

 void RenderBox::paintClippingMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     if (!paintInfo.shouldPaintWithinRoot(*this) || style().visibility() != Visibility::Visible || paintInfo.phase != PaintPhase::ClippingMask || paintInfo.context().paintingDisabled())
         return;

     LayoutRect paintRect = LayoutRect(paintOffset, size());
     paintInfo.context().fillRect(snappedIntRect(paintRect), Color::black);
 }

 void RenderBox::paintMaskImages(const PaintInfo& paintInfo, const LayoutRect& paintRect)
 {
     // Figure out if we need to push a transparency layer to render our mask.
     bool pushTransparencyLayer = false;
     bool compositedMask = hasLayer() && layer()->hasCompositedMask();
     bool flattenCompositingLayers = paintInfo.paintBehavior.contains(PaintBehavior::FlattenCompositingLayers);
     CompositeOperator compositeOp = CompositeSourceOver;

     bool allMaskImagesLoaded = true;

     if (!compositedMask || flattenCompositingLayers) {
         pushTransparencyLayer = true;

         // Don't render a masked element until all the mask images have loaded, to prevent a flash of unmasked content.
         if (auto* maskBoxImage = style().maskBoxImage().image())
             allMaskImagesLoaded &= maskBoxImage->isLoaded();

         allMaskImagesLoaded &= style().maskLayers().imagesAreLoaded();

         paintInfo.context().setCompositeOperation(CompositeDestinationIn);
         paintInfo.context().beginTransparencyLayer(1);
         compositeOp = CompositeSourceOver;
     }

     if (allMaskImagesLoaded) {
         paintFillLayers(paintInfo, Color(), style().maskLayers(), paintRect, BackgroundBleedNone, compositeOp);
         paintNinePieceImage(paintInfo.context(), paintRect, style(), style().maskBoxImage(), compositeOp);
     }

     if (pushTransparencyLayer)
         paintInfo.context().endTransparencyLayer();
 }

 LayoutRect RenderBox::maskClipRect(const LayoutPoint& paintOffset)
 {
     const NinePieceImage& maskBoxImage = style().maskBoxImage();
     if (maskBoxImage.image()) {
         LayoutRect borderImageRect = borderBoxRect();

         // Apply outsets to the border box.
         borderImageRect.expand(style().maskBoxImageOutsets());
         return borderImageRect;
     }

     LayoutRect result;
     LayoutRect borderBox = borderBoxRect();
     for (auto* maskLayer = &style().maskLayers(); maskLayer; maskLayer = maskLayer->next()) {
         if (maskLayer->image()) {
             // Masks should never have fixed attachment, so it's OK for paintContainer to be null.
             result.unite(calculateBackgroundImageGeometry(nullptr, *maskLayer, paintOffset, borderBox).destRect());
         }
     }
     return result;
 }

 void RenderBox::paintFillLayers(const PaintInfo& paintInfo, const Color& color, const FillLayer& fillLayer, const LayoutRect& rect,
     BackgroundBleedAvoidance bleedAvoidance, CompositeOperator op, RenderElement* backgroundObject)
 {
     Vector<const FillLayer*, 8> layers;
     bool shouldDrawBackgroundInSeparateBuffer = false;

     for (auto* layer = &fillLayer; layer; layer = layer->next()) {
         layers.append(layer);

         if (layer->blendMode() != BlendMode::Normal)
             shouldDrawBackgroundInSeparateBuffer = true;

         // Stop traversal when an opaque layer is encountered.
         // FIXME: It would be possible for the following occlusion culling test to be more aggressive
         // on layers with no repeat by testing whether the image covers the layout rect.
         // Testing that here would imply duplicating a lot of calculations that are currently done in
         // RenderBoxModelObject::paintFillLayerExtended. A more efficient solution might be to move
         // the layer recursion into paintFillLayerExtended, or to compute the layer geometry here
         // and pass it down.

         // The clipOccludesNextLayers condition must be evaluated first to avoid short-circuiting.
         if (layer->clipOccludesNextLayers(layer == &fillLayer) && layer->hasOpaqueImage(*this) && layer->image()->canRender(this, style().effectiveZoom()) && layer->hasRepeatXY() && layer->blendMode() == BlendMode::Normal)
             break;
     }

     auto& context = paintInfo.context();
     auto baseBgColorUsage = BaseBackgroundColorUse;

     if (shouldDrawBackgroundInSeparateBuffer) {
         paintFillLayer(paintInfo, color, *layers.last(), rect, bleedAvoidance, op, backgroundObject, BaseBackgroundColorOnly);
         baseBgColorUsage = BaseBackgroundColorSkip;
         context.beginTransparencyLayer(1);
     }

     auto topLayer = layers.rend();
     for (auto it = layers.rbegin(); it != topLayer; ++it)
         paintFillLayer(paintInfo, color, **it, rect, bleedAvoidance, op, backgroundObject, baseBgColorUsage);

     if (shouldDrawBackgroundInSeparateBuffer)
         context.endTransparencyLayer();
 }

 void RenderBox::paintFillLayer(const PaintInfo& paintInfo, const Color& c, const FillLayer& fillLayer, const LayoutRect& rect,
     BackgroundBleedAvoidance bleedAvoidance, CompositeOperator op, RenderElement* backgroundObject, BaseBackgroundColorUsage baseBgColorUsage)
 {
     paintFillLayerExtended(paintInfo, c, fillLayer, rect, bleedAvoidance, nullptr, LayoutSize(), op, backgroundObject, baseBgColorUsage);
 }

 static bool layersUseImage(WrappedImagePtr image, const FillLayer& layers)
 {
     for (auto* layer = &layers; layer; layer = layer->next()) {
         if (layer->image() && image == layer->image()->data())
             return true;
     }
     return false;
 }

 void RenderBox::imageChanged(WrappedImagePtr image, const IntRect*)
 {
     if (!parent())
         return;

     if ((style().borderImage().image() && style().borderImage().image()->data() == image) ||
         (style().maskBoxImage().image() && style().maskBoxImage().image()->data() == image)) {
         repaint();
         return;
     }

     ShapeValue* shapeOutsideValue = style().shapeOutside();
     if (!view().frameView().layoutContext().isInRenderTreeLayout() && isFloating() && shapeOutsideValue && shapeOutsideValue->image() && shapeOutsideValue->image()->data() == image) {
         ShapeOutsideInfo::ensureInfo(*this).markShapeAsDirty();
         markShapeOutsideDependentsForLayout();
     }

     bool didFullRepaint = repaintLayerRectsForImage(image, style().backgroundLayers(), true);
     if (!didFullRepaint)
         repaintLayerRectsForImage(image, style().maskLayers(), false);

     if (!isComposited())
         return;

     if (layer()->hasCompositedMask() && layersUseImage(image, style().maskLayers()))
         layer()->contentChanged(MaskImageChanged);
     if (layersUseImage(image, style().backgroundLayers()))
         layer()->contentChanged(BackgroundImageChanged);
 }

 bool RenderBox::repaintLayerRectsForImage(WrappedImagePtr image, const FillLayer& layers, bool drawingBackground)
 {
     LayoutRect rendererRect;
     RenderBox* layerRenderer = nullptr;

     for (auto* layer = &layers; layer; layer = layer->next()) {
         if (layer->image() && image == layer->image()->data() && layer->image()->canRender(this, style().effectiveZoom())) {
             // Now that we know this image is being used, compute the renderer and the rect if we haven't already.
             bool drawingRootBackground = drawingBackground && (isDocumentElementRenderer() || (isBody() && !document().documentElement()->renderer()->hasBackground()));
             if (!layerRenderer) {
                 if (drawingRootBackground) {
                     layerRenderer = &view();

                     LayoutUnit rw = downcast<RenderView>(*layerRenderer).frameView().contentsWidth();
                     LayoutUnit rh = downcast<RenderView>(*layerRenderer).frameView().contentsHeight();

                     rendererRect = LayoutRect(-layerRenderer->marginLeft(),
                         -layerRenderer->marginTop(),
                         std::max(layerRenderer->width() + layerRenderer->horizontalMarginExtent() + layerRenderer->borderLeft() + layerRenderer->borderRight(), rw),
                         std::max(layerRenderer->height() + layerRenderer->verticalMarginExtent() + layerRenderer->borderTop() + layerRenderer->borderBottom(), rh));
                 } else {
                     layerRenderer = this;
                     rendererRect = borderBoxRect();
                 }
             }
             // FIXME: Figure out how to pass absolute position to calculateBackgroundImageGeometry (for pixel snapping)
             BackgroundImageGeometry geometry = layerRenderer->calculateBackgroundImageGeometry(nullptr, *layer, LayoutPoint(), rendererRect);
             if (geometry.hasNonLocalGeometry()) {
                 // Rather than incur the costs of computing the paintContainer for renderers with fixed backgrounds
                 // in order to get the right destRect, just repaint the entire renderer.
                 layerRenderer->repaint();
                 return true;
             }

             LayoutRect rectToRepaint = geometry.destRect();
             bool shouldClipToLayer = true;

             // If this is the root background layer, we may need to extend the repaintRect if the FrameView has an
             // extendedBackground. We should only extend the rect if it is already extending the full width or height
             // of the rendererRect.
             if (drawingRootBackground && view().frameView().hasExtendedBackgroundRectForPainting()) {
                 shouldClipToLayer = false;
                 IntRect extendedBackgroundRect = view().frameView().extendedBackgroundRectForPainting();
                 if (rectToRepaint.width() == rendererRect.width()) {
                     rectToRepaint.move(extendedBackgroundRect.x(), 0);
                     rectToRepaint.setWidth(extendedBackgroundRect.width());
                 }
                 if (rectToRepaint.height() == rendererRect.height()) {
                     rectToRepaint.move(0, extendedBackgroundRect.y());
                     rectToRepaint.setHeight(extendedBackgroundRect.height());
                 }
             }

             layerRenderer->repaintRectangle(rectToRepaint, shouldClipToLayer);
             if (geometry.destRect() == rendererRect)
                 return true;
         }
     }
     return false;
 }

 bool RenderBox::pushContentsClip(PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset)
 {
     if (paintInfo.phase == PaintPhase::BlockBackground || paintInfo.phase == PaintPhase::SelfOutline || paintInfo.phase == PaintPhase::Mask)
         return false;

     bool isControlClip = hasControlClip();
     bool isOverflowClip = hasOverflowClip() && !layer()->isSelfPaintingLayer();

     if (!isControlClip && !isOverflowClip)
         return false;

     if (paintInfo.phase == PaintPhase::Outline)
         paintInfo.phase = PaintPhase::ChildOutlines;
     else if (paintInfo.phase == PaintPhase::ChildBlockBackground) {
         paintInfo.phase = PaintPhase::BlockBackground;
         paintObject(paintInfo, accumulatedOffset);
         paintInfo.phase = PaintPhase::ChildBlockBackgrounds;
     }
     float deviceScaleFactor = document().deviceScaleFactor();
     FloatRect clipRect = snapRectToDevicePixels((isControlClip ? controlClipRect(accumulatedOffset) : overflowClipRect(accumulatedOffset, nullptr, IgnoreOverlayScrollbarSize, paintInfo.phase)), deviceScaleFactor);
     paintInfo.context().save();
     if (style().hasBorderRadius())
         paintInfo.context().clipRoundedRect(style().getRoundedInnerBorderFor(LayoutRect(accumulatedOffset, size())).pixelSnappedRoundedRectForPainting(deviceScaleFactor));
     paintInfo.context().clip(clipRect);

     if (paintInfo.phase == PaintPhase::EventRegion)
         paintInfo.eventRegionContext->pushClip(enclosingIntRect(clipRect));

     return true;
 }

 void RenderBox::popContentsClip(PaintInfo& paintInfo, PaintPhase originalPhase, const LayoutPoint& accumulatedOffset)
 {
     ASSERT(hasControlClip() || (hasOverflowClip() && !layer()->isSelfPaintingLayer()));

     if (paintInfo.phase == PaintPhase::EventRegion)
         paintInfo.eventRegionContext->popClip();

     paintInfo.context().restore();
     if (originalPhase == PaintPhase::Outline) {
         paintInfo.phase = PaintPhase::SelfOutline;
         paintObject(paintInfo, accumulatedOffset);
         paintInfo.phase = originalPhase;
     } else if (originalPhase == PaintPhase::ChildBlockBackground)
         paintInfo.phase = originalPhase;
 }

 LayoutRect RenderBox::overflowClipRect(const LayoutPoint& location, RenderFragmentContainer* fragment, OverlayScrollbarSizeRelevancy relevancy, PaintPhase)
 {
     // FIXME: When overflow-clip (CSS3) is implemented, we'll obtain the property
     // here.
     LayoutRect clipRect = borderBoxRectInFragment(fragment);
     clipRect.setLocation(location + clipRect.location() + LayoutSize(borderLeft(), borderTop()));
     clipRect.setSize(clipRect.size() - LayoutSize(borderLeft() + borderRight(), borderTop() + borderBottom()));

     // Subtract out scrollbars if we have them.
     if (layer()) {
         if (shouldPlaceBlockDirectionScrollbarOnLeft())
             clipRect.move(layer()->verticalScrollbarWidth(relevancy), 0);
         clipRect.contract(layer()->verticalScrollbarWidth(relevancy), layer()->horizontalScrollbarHeight(relevancy));
     }

     return clipRect;
 }

 LayoutRect RenderBox::clipRect(const LayoutPoint& location, RenderFragmentContainer* fragment)
 {
     LayoutRect borderBoxRect = borderBoxRectInFragment(fragment);
     LayoutRect clipRect = LayoutRect(borderBoxRect.location() + location, borderBoxRect.size());

     if (!style().clipLeft().isAuto()) {
         LayoutUnit c = valueForLength(style().clipLeft(), borderBoxRect.width());
         clipRect.move(c, 0_lu);
         clipRect.contract(c, 0_lu);
     }

     // We don't use the fragment-specific border box's width and height since clip offsets are (stupidly) specified
     // from the left and top edges. Therefore it's better to avoid constraining to smaller widths and heights.

     if (!style().clipRight().isAuto())
         clipRect.contract(width() - valueForLength(style().clipRight(), width()), 0_lu);

     if (!style().clipTop().isAuto()) {
         LayoutUnit c = valueForLength(style().clipTop(), borderBoxRect.height());
         clipRect.move(0_lu, c);
         clipRect.contract(0_lu, c);
     }

     if (!style().clipBottom().isAuto())
         clipRect.contract(0_lu, height() - valueForLength(style().clipBottom(), height()));

     return clipRect;
 }

 LayoutUnit RenderBox::shrinkLogicalWidthToAvoidFloats(LayoutUnit childMarginStart, LayoutUnit childMarginEnd, const RenderBlock& cb, RenderFragmentContainer* fragment) const
 {
     RenderFragmentContainer* containingBlockFragment = nullptr;
     LayoutUnit logicalTopPosition = logicalTop();
     if (fragment) {
         LayoutUnit offsetFromLogicalTopOfFragment = fragment ? fragment->logicalTopForFragmentedFlowContent() - offsetFromLogicalTopOfFirstPage() : 0_lu;
         logicalTopPosition = std::max(logicalTopPosition, logicalTopPosition + offsetFromLogicalTopOfFragment);
         containingBlockFragment = cb.clampToStartAndEndFragments(fragment);
     }

     LayoutUnit logicalHeight = cb.logicalHeightForChild(*this);
     LayoutUnit result = cb.availableLogicalWidthForLineInFragment(logicalTopPosition, DoNotIndentText, containingBlockFragment, logicalHeight) - childMarginStart - childMarginEnd;

     // We need to see if margins on either the start side or the end side can contain the floats in question. If they can,
     // then just using the line width is inaccurate. In the case where a float completely fits, we don't need to use the line
     // offset at all, but can instead push all the way to the content edge of the containing block. In the case where the float
     // doesn't fit, we can use the line offset, but we need to grow it by the margin to reflect the fact that the margin was
     // "consumed" by the float. Negative margins aren't consumed by the float, and so we ignore them.
     if (childMarginStart > 0) {
         LayoutUnit startContentSide = cb.startOffsetForContent(containingBlockFragment);
         LayoutUnit startContentSideWithMargin = startContentSide + childMarginStart;
         LayoutUnit startOffset = cb.startOffsetForLineInFragment(logicalTopPosition, DoNotIndentText, containingBlockFragment, logicalHeight);
         if (startOffset > startContentSideWithMargin)
             result += childMarginStart;
         else
             result += startOffset - startContentSide;
     }

     if (childMarginEnd > 0) {
         LayoutUnit endContentSide = cb.endOffsetForContent(containingBlockFragment);
         LayoutUnit endContentSideWithMargin = endContentSide + childMarginEnd;
         LayoutUnit endOffset = cb.endOffsetForLineInFragment(logicalTopPosition, DoNotIndentText, containingBlockFragment, logicalHeight);
         if (endOffset > endContentSideWithMargin)
             result += childMarginEnd;
         else
             result += endOffset - endContentSide;
     }

     return result;
 }

 LayoutUnit RenderBox::containingBlockLogicalWidthForContent() const
 {
     if (hasOverrideContainingBlockContentLogicalWidth()) {
         if (auto overrideLogicalWidth = overrideContainingBlockContentLogicalWidth())
             return overrideLogicalWidth.value();
     }

     if (RenderBlock* cb = containingBlock())
         return cb->availableLogicalWidth();
     return 0_lu;
 }

 LayoutUnit RenderBox::containingBlockLogicalHeightForContent(AvailableLogicalHeightType heightType) const
 {
     if (hasOverrideContainingBlockContentLogicalHeight()) {
         if (auto overrideLogicalHeight = overrideContainingBlockContentLogicalHeight())
             return overrideLogicalHeight.value();
     }

     if (RenderBlock* cb = containingBlock())
         return cb->availableLogicalHeight(heightType);
     return 0_lu;
 }

 LayoutUnit RenderBox::containingBlockLogicalWidthForContentInFragment(RenderFragmentContainer* fragment) const
 {
     if (!fragment)
         return containingBlockLogicalWidthForContent();

     RenderBlock* cb = containingBlock();
     RenderFragmentContainer* containingBlockFragment = cb->clampToStartAndEndFragments(fragment);
     // FIXME: It's unclear if a fragment's content should use the containing block's override logical width.
     // If it should, the following line should call containingBlockLogicalWidthForContent.
     LayoutUnit result = cb->availableLogicalWidth();
     RenderBoxFragmentInfo* boxInfo = cb->renderBoxFragmentInfo(containingBlockFragment);
     if (!boxInfo)
         return result;
     return std::max<LayoutUnit>(0, result - (cb->logicalWidth() - boxInfo->logicalWidth()));
 }

 LayoutUnit RenderBox::containingBlockAvailableLineWidthInFragment(RenderFragmentContainer* fragment) const
 {
     RenderBlock* cb = containingBlock();
     RenderFragmentContainer* containingBlockFragment = nullptr;
     LayoutUnit logicalTopPosition = logicalTop();
     if (fragment) {
         LayoutUnit offsetFromLogicalTopOfFragment = fragment ? fragment->logicalTopForFragmentedFlowContent() - offsetFromLogicalTopOfFirstPage() : 0_lu;
         logicalTopPosition = std::max(logicalTopPosition, logicalTopPosition + offsetFromLogicalTopOfFragment);
         containingBlockFragment = cb->clampToStartAndEndFragments(fragment);
     }
     return cb->availableLogicalWidthForLineInFragment(logicalTopPosition, DoNotIndentText, containingBlockFragment, availableLogicalHeight(IncludeMarginBorderPadding));
 }

 LayoutUnit RenderBox::perpendicularContainingBlockLogicalHeight() const
 {
     if (hasOverrideContainingBlockContentLogicalHeight()) {
         if (auto overrideLogicalHeight = overrideContainingBlockContentLogicalHeight())
             return overrideLogicalHeight.value();
     }

     RenderBlock* cb = containingBlock();
     if (cb->hasOverrideContentLogicalHeight())
         return cb->overrideContentLogicalHeight();

     const RenderStyle& containingBlockStyle = cb->style();
     Length logicalHeightLength = containingBlockStyle.logicalHeight();

     // FIXME: For now just support fixed heights.  Eventually should support percentage heights as well.
     if (!logicalHeightLength.isFixed()) {
         LayoutUnit fillFallbackExtent = containingBlockStyle.isHorizontalWritingMode() ? view().frameView().visibleHeight() : view().frameView().visibleWidth();
         LayoutUnit fillAvailableExtent = containingBlock()->availableLogicalHeight(ExcludeMarginBorderPadding);
         view().addPercentHeightDescendant(const_cast<RenderBox&>(*this));
         // FIXME: https://bugs.webkit.org/show_bug.cgi?id=158286 We also need to perform the same percentHeightDescendant treatment to the element which dictates the return value for containingBlock()->availableLogicalHeight() above.
         return std::min(fillAvailableExtent, fillFallbackExtent);
     }

     // Use the content box logical height as specified by the style.
     return cb->adjustContentBoxLogicalHeightForBoxSizing(LayoutUnit(logicalHeightLength.value()));
 }

 void RenderBox::mapLocalToContainer(const RenderLayerModelObject* repaintContainer, TransformState& transformState, MapCoordinatesFlags mode, bool* wasFixed) const
 {
     if (repaintContainer == this)
         return;

     if (!repaintContainer && view().frameView().layoutContext().isPaintOffsetCacheEnabled()) {
         auto* layoutState = view().frameView().layoutContext().layoutState();
         LayoutSize offset = layoutState->paintOffset() + locationOffset();
         if (style().hasInFlowPosition() && layer())
             offset += layer()->offsetForInFlowPosition();
         transformState.move(offset);
         return;
     }

     bool containerSkipped;
     RenderElement* container = this->container(repaintContainer, containerSkipped);
     if (!container)
         return;

     bool isFixedPos = isFixedPositioned();
     // If this box has a transform, it acts as a fixed position container for fixed descendants,
     // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
     if (hasTransform() && !isFixedPos)
         mode &= ~IsFixed;
     else if (isFixedPos)
         mode |= IsFixed;

     if (wasFixed)
         *wasFixed = mode & IsFixed;

     LayoutSize containerOffset = offsetFromContainer(*container, LayoutPoint(transformState.mappedPoint()));

     bool preserve3D = mode & UseTransforms && (container->style().preserves3D() || style().preserves3D());
     if (mode & UseTransforms && shouldUseTransformFromContainer(container)) {
         TransformationMatrix t;
         getTransformFromContainer(container, containerOffset, t);
         transformState.applyTransform(t, preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
     } else
         transformState.move(containerOffset.width(), containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);

     if (containerSkipped) {
         // There can't be a transform between repaintContainer and o, because transforms create containers, so it should be safe
         // to just subtract the delta between the repaintContainer and o.
         LayoutSize containerOffset = repaintContainer->offsetFromAncestorContainer(*container);
         transformState.move(-containerOffset.width(), -containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
         return;
     }

     mode &= ~ApplyContainerFlip;

     container->mapLocalToContainer(repaintContainer, transformState, mode, wasFixed);
 }

 const RenderObject* RenderBox::pushMappingToContainer(const RenderLayerModelObject* ancestorToStopAt, RenderGeometryMap& geometryMap) const
 {
     ASSERT(ancestorToStopAt != this);

     bool ancestorSkipped;
     RenderElement* container = this->container(ancestorToStopAt, ancestorSkipped);
     if (!container)
         return nullptr;

     bool isFixedPos = isFixedPositioned();
     LayoutSize adjustmentForSkippedAncestor;
     if (ancestorSkipped) {
         // There can't be a transform between repaintContainer and container, because transforms create containers, so it should be safe
         // to just subtract the delta between the ancestor and container.
         adjustmentForSkippedAncestor = -ancestorToStopAt->offsetFromAncestorContainer(*container);
     }

     bool offsetDependsOnPoint = false;
     LayoutSize containerOffset = offsetFromContainer(*container, LayoutPoint(), &offsetDependsOnPoint);

     bool preserve3D = container->style().preserves3D() || style().preserves3D();
     if (shouldUseTransformFromContainer(container) && (geometryMap.mapCoordinatesFlags() & UseTransforms)) {
         TransformationMatrix t;
         getTransformFromContainer(container, containerOffset, t);
         t.translateRight(adjustmentForSkippedAncestor.width(), adjustmentForSkippedAncestor.height());

         geometryMap.push(this, t, preserve3D, offsetDependsOnPoint, isFixedPos, hasTransform());
     } else {
         containerOffset += adjustmentForSkippedAncestor;
         geometryMap.push(this, containerOffset, preserve3D, offsetDependsOnPoint, isFixedPos, hasTransform());
     }

     return ancestorSkipped ? ancestorToStopAt : container;
 }

 void RenderBox::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, TransformState& transformState) const
 {
     bool isFixedPos = isFixedPositioned();
     if (hasTransform() && !isFixedPos) {
         // If this box has a transform, it acts as a fixed position container for fixed descendants,
         // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
         mode &= ~IsFixed;
     } else if (isFixedPos)
         mode |= IsFixed;

     RenderBoxModelObject::mapAbsoluteToLocalPoint(mode, transformState);
 }

 LayoutSize RenderBox::offsetFromContainer(RenderElement& container, const LayoutPoint&, bool* offsetDependsOnPoint) const
 {
     // A fragment "has" boxes inside it without being their container.
     ASSERT(&container == this->container() || is<RenderFragmentContainer>(container));

     LayoutSize offset;
     if (isInFlowPositioned())
         offset += offsetForInFlowPosition();

     if (!isInline() || isReplaced())
         offset += topLeftLocationOffset();

     if (is<RenderBox>(container))
         offset -= toLayoutSize(downcast<RenderBox>(container).scrollPosition());

     if (isAbsolutelyPositioned() && container.isInFlowPositioned() && is<RenderInline>(container))
         offset += downcast<RenderInline>(container).offsetForInFlowPositionedInline(this);

     if (offsetDependsOnPoint)
         *offsetDependsOnPoint |= is<RenderFragmentedFlow>(container);

     return offset;
 }

 std::unique_ptr<InlineElementBox> RenderBox::createInlineBox()
 {
     return makeUnique<InlineElementBox>(*this);
 }

 void RenderBox::dirtyLineBoxes(bool fullLayout)
 {
     if (!m_inlineBoxWrapper)
         return;

     if (fullLayout) {
         delete m_inlineBoxWrapper;
         m_inlineBoxWrapper = nullptr;
     } else
         m_inlineBoxWrapper->dirtyLineBoxes();
 }

 void RenderBox::positionLineBox(InlineElementBox& box)
 {
     if (isOutOfFlowPositioned()) {
         // Cache the x position only if we were an DisplayType::Inline type originally.
         bool wasInline = style().isOriginalDisplayInlineType();
         if (wasInline) {
             // The value is cached in the xPos of the box.  We only need this value if
             // our object was inline originally, since otherwise it would have ended up underneath
             // the inlines.
             RootInlineBox& rootBox = box.root();
             rootBox.blockFlow().setStaticInlinePositionForChild(*this, rootBox.lineTopWithLeading(), LayoutUnit::fromFloatRound(box.logicalLeft()));
             if (style().hasStaticInlinePosition(box.isHorizontal()))
                 setChildNeedsLayout(MarkOnlyThis); // Just mark the positioned object as needing layout, so it will update its position properly.
         } else {
             // Our object was a block originally, so we make our normal flow position be
             // just below the line box (as though all the inlines that came before us got
             // wrapped in an anonymous block, which is what would have happened had we been
             // in flow).  This value was cached in the y() of the box.
             layer()->setStaticBlockPosition(LayoutUnit(box.logicalTop()));
             if (style().hasStaticBlockPosition(box.isHorizontal()))
                 setChildNeedsLayout(MarkOnlyThis); // Just mark the positioned object as needing layout, so it will update its position properly.
         }
         return;
     }

     if (isReplaced()) {
         setLocation(LayoutPoint(box.topLeft()));
         setInlineBoxWrapper(&box);
     }
 }

 void RenderBox::deleteLineBoxWrapper()
 {
     if (!m_inlineBoxWrapper)
         return;

     if (!renderTreeBeingDestroyed())
         m_inlineBoxWrapper->removeFromParent();
     delete m_inlineBoxWrapper;
     m_inlineBoxWrapper = nullptr;
 }

 LayoutRect RenderBox::clippedOverflowRectForRepaint(const RenderLayerModelObject* repaintContainer) const
 {
     if (style().visibility() != Visibility::Visible && !enclosingLayer()->hasVisibleContent())
         return LayoutRect();
     LayoutRect r = visualOverflowRect();
     // FIXME: layoutDelta needs to be applied in parts before/after transforms and
     // repaint containers. https://bugs.webkit.org/show_bug.cgi?id=23308
     r.move(view().frameView().layoutContext().layoutDelta());
     return computeRectForRepaint(r, repaintContainer);
 }

 LayoutRect RenderBox::computeVisibleRectUsingPaintOffset(const LayoutRect& rect) const
 {
     LayoutRect adjustedRect = rect;
     auto* layoutState = view().frameView().layoutContext().layoutState();

     if (layer() && layer()->transform())
         adjustedRect = LayoutRect(encloseRectToDevicePixels(layer()->transform()->mapRect(adjustedRect), document().deviceScaleFactor()));

     // We can't trust the bits on RenderObject, because this might be called while re-resolving style.
     if (style().hasInFlowPosition() && layer())
         adjustedRect.move(layer()->offsetForInFlowPosition());

     adjustedRect.moveBy(location());
     adjustedRect.move(layoutState->paintOffset());
     if (layoutState->isClipped())
         adjustedRect.intersect(layoutState->clipRect());
     return adjustedRect;
 }

 Optional<LayoutRect> RenderBox::computeVisibleRectInContainer(const LayoutRect& rect, const RenderLayerModelObject* container, VisibleRectContext context) const
 {
     // The rect we compute at each step is shifted by our x/y offset in the parent container's coordinate space.
     // Only when we cross a writing mode boundary will we have to possibly flipForWritingMode (to convert into a more appropriate
     // offset corner for the enclosing container).  This allows for a fully RL or BT document to repaint
     // properly even during layout, since the rect remains flipped all the way until the end.
     //
     // RenderView::computeVisibleRectInContainer then converts the rect to physical coordinates. We also convert to
     // physical when we hit a repaint container boundary. Therefore the final rect returned is always in the
     // physical coordinate space of the container.
     const RenderStyle& styleToUse = style();
     // Paint offset cache is only valid for root-relative, non-fixed position repainting
     if (view().frameView().layoutContext().isPaintOffsetCacheEnabled() && !container && styleToUse.position() != PositionType::Fixed && !context.m_options.contains(VisibleRectContextOption::UseEdgeInclusiveIntersection))
         return computeVisibleRectUsingPaintOffset(rect);

     LayoutRect adjustedRect = rect;
     if (hasReflection())
         adjustedRect.unite(reflectedRect(adjustedRect));

     if (container == this) {
         if (container->style().isFlippedBlocksWritingMode())
             flipForWritingMode(adjustedRect);
         return adjustedRect;
     }

     bool containerIsSkipped;
     auto* localContainer = this->container(container, containerIsSkipped);
     if (!localContainer)
         return adjustedRect;

     // This code isn't necessary for in-flow RenderFragmentedFlows.
     // Don't add the location of the fragment in the flow thread for absolute positioned
     // elements because their absolute position already pushes them down through
     // the fragments so adding this here and then adding the topLeft again would cause
     // us to add the height twice.
     // The same logic applies for elements flowed directly into the flow thread. Their topLeft member
     // will already contain the portion rect of the fragment.
     auto position = styleToUse.position();
     if (localContainer->isOutOfFlowRenderFragmentedFlow() && position != PositionType::Absolute && containingBlock() != enclosingFragmentedFlow()) {
         RenderFragmentContainer* firstFragment = nullptr;
         RenderFragmentContainer* lastFragment = nullptr;
         if (downcast<RenderFragmentedFlow>(*localContainer).getFragmentRangeForBox(this, firstFragment, lastFragment))
             adjustedRect.moveBy(firstFragment->fragmentedFlowPortionRect().location());
     }

     if (isWritingModeRoot()) {
         if (!isOutOfFlowPositioned() || !context.m_dirtyRectIsFlipped) {
             flipForWritingMode(adjustedRect);
             context.m_dirtyRectIsFlipped = true;
         }
     }

     LayoutSize locationOffset = this->locationOffset();
     // FIXME: This is needed as long as RenderWidget snaps to integral size/position.
     if (isRenderReplaced() && isWidget()) {
         LayoutSize flooredLocationOffset = toIntSize(flooredIntPoint(locationOffset));
         adjustedRect.expand(locationOffset - flooredLocationOffset);
         locationOffset = flooredLocationOffset;
     }

     if (is<RenderMultiColumnFlow>(this)) {
         // We won't normally run this code. Only when the container is null (i.e., we're trying
         // to get the rect in view coordinates) will we come in here, since normally container
         // will be set and we'll stop at the flow thread. This case is mainly hit by the check for whether
         // or not images should animate.
         // FIXME: Just as with offsetFromContainer, we aren't really handling objects that span
         // multiple columns properly.
         LayoutPoint physicalPoint(flipForWritingMode(adjustedRect.location()));
         if (auto* fragment = downcast<RenderMultiColumnFlow>(*this).physicalTranslationFromFlowToFragment((physicalPoint))) {
             adjustedRect.setLocation(fragment->flipForWritingMode(physicalPoint));
             return fragment->computeVisibleRectInContainer(adjustedRect, container, context);
         }
     }

     LayoutPoint topLeft = adjustedRect.location();
     topLeft.move(locationOffset);

     // We are now in our parent container's coordinate space. Apply our transform to obtain a bounding box
     // in the parent's coordinate space that encloses us.
     if (hasLayer() && layer()->transform()) {
         context.m_hasPositionFixedDescendant = position == PositionType::Fixed;
         adjustedRect = LayoutRect(encloseRectToDevicePixels(layer()->transform()->mapRect(adjustedRect), document().deviceScaleFactor()));
         topLeft = adjustedRect.location();
         topLeft.move(locationOffset);
     } else if (position == PositionType::Fixed)
         context.m_hasPositionFixedDescendant = true;

     if (position == PositionType::Absolute && localContainer->isInFlowPositioned() && is<RenderInline>(*localContainer))
         topLeft += downcast<RenderInline>(*localContainer).offsetForInFlowPositionedInline(this);
     else if (styleToUse.hasInFlowPosition() && layer()) {
         // Apply the relative position offset when invalidating a rectangle.  The layer
         // is translated, but the render box isn't, so we need to do this to get the
         // right dirty rect.  Since this is called from RenderObject::setStyle, the relative position
         // flag on the RenderObject has been cleared, so use the one on the style().
         topLeft += layer()->offsetForInFlowPosition();
     }

     // FIXME: We ignore the lightweight clipping rect that controls use, since if |o| is in mid-layout,
     // its controlClipRect will be wrong. For overflow clip we use the values cached by the layer.
     adjustedRect.setLocation(topLeft);
     if (localContainer->hasOverflowClip()) {
         RenderBox& containerBox = downcast<RenderBox>(*localContainer);
         bool isEmpty = !containerBox.applyCachedClipAndScrollPosition(adjustedRect, container, context);
         if (isEmpty) {
             if (context.m_options.contains(VisibleRectContextOption::UseEdgeInclusiveIntersection))
                 return WTF::nullopt;
             return adjustedRect;
         }
     }

     if (containerIsSkipped) {
         // If the container is below localContainer, then we need to map the rect into container's coordinates.
         LayoutSize containerOffset = container->offsetFromAncestorContainer(*localContainer);
         adjustedRect.move(-containerOffset);
         return adjustedRect;
     }
     return localContainer->computeVisibleRectInContainer(adjustedRect, container, context);
 }

 void RenderBox::repaintDuringLayoutIfMoved(const LayoutRect& oldRect)
 {
     if (oldRect.location() != m_frameRect.location()) {
         LayoutRect newRect = m_frameRect;
         // The child moved.  Invalidate the object's old and new positions.  We have to do this
         // since the object may not have gotten a layout.
         m_frameRect = oldRect;
         repaint();
         repaintOverhangingFloats(true);
         m_frameRect = newRect;
         repaint();
         repaintOverhangingFloats(true);
     }
 }

 void RenderBox::repaintOverhangingFloats(bool)
 {
 }

 void RenderBox::updateLogicalWidth()
 {
     LogicalExtentComputedValues computedValues;
     computeLogicalWidthInFragment(computedValues);

     setLogicalWidth(computedValues.m_extent);
     setLogicalLeft(computedValues.m_position);
     setMarginStart(computedValues.m_margins.m_start);
     setMarginEnd(computedValues.m_margins.m_end);
 }

 void RenderBox::computeLogicalWidthInFragment(LogicalExtentComputedValues& computedValues, RenderFragmentContainer* fragment) const
 {
     computedValues.m_extent = logicalWidth();
     computedValues.m_position = logicalLeft();
     computedValues.m_margins.m_start = marginStart();
     computedValues.m_margins.m_end = marginEnd();

     if (isOutOfFlowPositioned()) {
         // FIXME: This calculation is not patched for block-flow yet.
         // https://bugs.webkit.org/show_bug.cgi?id=46500
         computePositionedLogicalWidth(computedValues, fragment);
         return;
     }

     // If layout is limited to a subtree, the subtree root's logical width does not change.
     if (element() && !view().frameView().layoutContext().isLayoutPending() && view().frameView().layoutContext().subtreeLayoutRoot() == this)
         return;

     // The parent box is flexing us, so it has increased or decreased our
     // width.  Use the width from the style context.
     // FIXME: Account for block-flow in flexible boxes.
     // https://bugs.webkit.org/show_bug.cgi?id=46418
     if (hasOverrideContentLogicalWidth() && (isRubyRun() || style().borderFit() == BorderFit::Lines || (parent()->isFlexibleBoxIncludingDeprecated()))) {
         computedValues.m_extent = overrideContentLogicalWidth() + borderAndPaddingLogicalWidth();
         return;
     }

     // FIXME: Account for block-flow in flexible boxes.
     // https://bugs.webkit.org/show_bug.cgi?id=46418
     bool inVerticalBox = parent()->isDeprecatedFlexibleBox() && (parent()->style().boxOrient() == BoxOrient::Vertical);
     bool stretching = (parent()->style().boxAlign() == BoxAlignment::Stretch);
     // FIXME: Stretching is the only reason why we don't want the box to be treated as a replaced element, so we could perhaps
     // refactor all this logic, not only for flex and grid since alignment is intended to be applied to any block.
     bool treatAsReplaced = shouldComputeSizeAsReplaced() && (!inVerticalBox || !stretching);
     treatAsReplaced = treatAsReplaced && (!isGridItem() || !hasStretchedLogicalWidth());

     const RenderStyle& styleToUse = style();
     Length logicalWidthLength = treatAsReplaced ? Length(computeReplacedLogicalWidth(), Fixed) : styleToUse.logicalWidth();

     RenderBlock& cb = *containingBlock();
     LayoutUnit containerLogicalWidth = std::max<LayoutUnit>(0, containingBlockLogicalWidthForContentInFragment(fragment));
     bool hasPerpendicularContainingBlock = cb.isHorizontalWritingMode() != isHorizontalWritingMode();

     if (isInline() && !isInlineBlockOrInlineTable()) {
         // just calculate margins
         computedValues.m_margins.m_start = minimumValueForLength(styleToUse.marginStart(), containerLogicalWidth);
         computedValues.m_margins.m_end = minimumValueForLength(styleToUse.marginEnd(), containerLogicalWidth);
         if (treatAsReplaced)
             computedValues.m_extent = std::max(LayoutUnit(floatValueForLength(logicalWidthLength, 0) + borderAndPaddingLogicalWidth()), minPreferredLogicalWidth());
         return;
     }

     LayoutUnit containerWidthInInlineDirection = containerLogicalWidth;
     if (hasPerpendicularContainingBlock)
         containerWidthInInlineDirection = perpendicularContainingBlockLogicalHeight();

     // Width calculations
     if (treatAsReplaced) {
         computedValues.m_extent = logicalWidthLength.value() + borderAndPaddingLogicalWidth();
     } else {
         LayoutUnit preferredWidth = computeLogicalWidthInFragmentUsing(MainOrPreferredSize, styleToUse.logicalWidth(), containerWidthInInlineDirection, cb, fragment);
         computedValues.m_extent = constrainLogicalWidthInFragmentByMinMax(preferredWidth, containerWidthInInlineDirection, cb, fragment);
     }

     // Margin calculations.
     if (hasPerpendicularContainingBlock || isFloating() || isInline()) {
         computedValues.m_margins.m_start = minimumValueForLength(styleToUse.marginStart(), containerLogicalWidth);
         computedValues.m_margins.m_end = minimumValueForLength(styleToUse.marginEnd(), containerLogicalWidth);
     } else {
         LayoutUnit containerLogicalWidthForAutoMargins = containerLogicalWidth;
         if (avoidsFloats() && cb.containsFloats())
             containerLogicalWidthForAutoMargins = containingBlockAvailableLineWidthInFragment(fragment);
         bool hasInvertedDirection = cb.style().isLeftToRightDirection() != style().isLeftToRightDirection();
         computeInlineDirectionMargins(cb, containerLogicalWidthForAutoMargins, computedValues.m_extent,
             hasInvertedDirection ? computedValues.m_margins.m_end : computedValues.m_margins.m_start,
             hasInvertedDirection ? computedValues.m_margins.m_start : computedValues.m_margins.m_end);
     }

     if (!hasPerpendicularContainingBlock && containerLogicalWidth && containerLogicalWidth != (computedValues.m_extent + computedValues.m_margins.m_start + computedValues.m_margins.m_end)
         && !isFloating() && !isInline() && !cb.isFlexibleBoxIncludingDeprecated()
 #if ENABLE(MATHML)
         // RenderMathMLBlocks take the size of their content so we must not adjust the margin to fill the container size.
         && !cb.isRenderMathMLBlock()
 #endif
         && !cb.isRenderGrid()
         ) {
         LayoutUnit newMarginTotal = containerLogicalWidth - computedValues.m_extent;
         bool hasInvertedDirection = cb.style().isLeftToRightDirection() != style().isLeftToRightDirection();
         if (hasInvertedDirection)
             computedValues.m_margins.m_start = newMarginTotal - computedValues.m_margins.m_end;
         else
             computedValues.m_margins.m_end = newMarginTotal - computedValues.m_margins.m_start;
     }
 }

 LayoutUnit RenderBox::fillAvailableMeasure(LayoutUnit availableLogicalWidth) const
 {
     LayoutUnit marginStart;
     LayoutUnit marginEnd;
     return fillAvailableMeasure(availableLogicalWidth, marginStart, marginEnd);
 }

 LayoutUnit RenderBox::fillAvailableMeasure(LayoutUnit availableLogicalWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const
 {
     marginStart = minimumValueForLength(style().marginStart(), availableLogicalWidth);
     marginEnd = minimumValueForLength(style().marginEnd(), availableLogicalWidth);
     return availableLogicalWidth - marginStart - marginEnd;
 }

 LayoutUnit RenderBox::computeIntrinsicLogicalWidthUsing(Length logicalWidthLength, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const
 {
     if (logicalWidthLength.type() == FillAvailable)
         return std::max(borderAndPadding, fillAvailableMeasure(availableLogicalWidth));

     LayoutUnit minLogicalWidth;
     LayoutUnit maxLogicalWidth;
     computeIntrinsicLogicalWidths(minLogicalWidth, maxLogicalWidth);

     if (logicalWidthLength.type() == MinContent)
         return minLogicalWidth + borderAndPadding;

     if (logicalWidthLength.type() == MaxContent)
         return maxLogicalWidth + borderAndPadding;

     if (logicalWidthLength.type() == FitContent) {
         minLogicalWidth += borderAndPadding;
         maxLogicalWidth += borderAndPadding;
         return std::max(minLogicalWidth, std::min(maxLogicalWidth, fillAvailableMeasure(availableLogicalWidth)));
     }

     ASSERT_NOT_REACHED();
     return 0;
 }

 LayoutUnit RenderBox::computeLogicalWidthInFragmentUsing(SizeType widthType, Length logicalWidth, LayoutUnit availableLogicalWidth,
     const RenderBlock& cb, RenderFragmentContainer* fragment) const
 {
     ASSERT(widthType == MinSize || widthType == MainOrPreferredSize || !logicalWidth.isAuto());
     if (widthType == MinSize && logicalWidth.isAuto())
         return adjustBorderBoxLogicalWidthForBoxSizing(0);

     if (!logicalWidth.isIntrinsicOrAuto()) {
         // FIXME: If the containing block flow is perpendicular to our direction we need to use the available logical height instead.
         return adjustBorderBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, availableLogicalWidth));
     }

     if (logicalWidth.isIntrinsic())
         return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth());

     LayoutUnit marginStart;
     LayoutUnit marginEnd;
     LayoutUnit logicalWidthResult = fillAvailableMeasure(availableLogicalWidth, marginStart, marginEnd);

     if (shrinkToAvoidFloats() && cb.containsFloats())
         logicalWidthResult = std::min(logicalWidthResult, shrinkLogicalWidthToAvoidFloats(marginStart, marginEnd, cb, fragment));

     if (widthType == MainOrPreferredSize && sizesLogicalWidthToFitContent(widthType))
         return std::max(minPreferredLogicalWidth(), std::min(maxPreferredLogicalWidth(), logicalWidthResult));
     return logicalWidthResult;
 }

 bool RenderBox::columnFlexItemHasStretchAlignment() const
 {
     // auto margins mean we don't stretch. Note that this function will only be
     // used for widths, so we don't have to check marginBefore/marginAfter.
     const auto& parentStyle = parent()->style();
     ASSERT(parentStyle.isColumnFlexDirection());
     if (style().marginStart().isAuto() || style().marginEnd().isAuto())
         return false;
     return style().resolvedAlignSelf(&parentStyle, containingBlock()->selfAlignmentNormalBehavior()).position() == ItemPosition::Stretch;
 }

 bool RenderBox::isStretchingColumnFlexItem() const
 {
     if (parent()->isDeprecatedFlexibleBox() && parent()->style().boxOrient() == BoxOrient::Vertical && parent()->style().boxAlign() == BoxAlignment::Stretch)
         return true;

     // We don't stretch multiline flexboxes because they need to apply line spacing (align-content) first.
     if (parent()->isFlexibleBox() && parent()->style().flexWrap() == FlexWrap::NoWrap && parent()->style().isColumnFlexDirection() && columnFlexItemHasStretchAlignment())
         return true;
     return false;
 }

 // FIXME: Can/Should we move this inside specific layout classes (flex. grid)? Can we refactor columnFlexItemHasStretchAlignment logic?
 bool RenderBox::hasStretchedLogicalWidth() const
 {
     auto& style = this->style();
     if (!style.logicalWidth().isAuto() || style.marginStart().isAuto() || style.marginEnd().isAuto())
         return false;
     RenderBlock* containingBlock = this->containingBlock();
     if (!containingBlock) {
         // We are evaluating align-self/justify-self, which default to 'normal' for the root element.
         // The 'normal' value behaves like 'start' except for Flexbox Items, which obviously should have a container.
         return false;
     }
     if (containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
         return style.resolvedAlignSelf(&containingBlock->style(), containingBlock->selfAlignmentNormalBehavior(this)).position() == ItemPosition::Stretch;
     return style.resolvedJustifySelf(&containingBlock->style(), containingBlock->selfAlignmentNormalBehavior(this)).position() == ItemPosition::Stretch;
 }

 bool RenderBox::sizesLogicalWidthToFitContent(SizeType widthType) const
 {
     // Marquees in WinIE are like a mixture of blocks and inline-blocks.  They size as though they're blocks,
     // but they allow text to sit on the same line as the marquee.
     if (isFloating() || (isInlineBlockOrInlineTable() && !isHTMLMarquee()))
         return true;

     if (isGridItem())
         return !hasStretchedLogicalWidth();

     // This code may look a bit strange.  Basically width:intrinsic should clamp the size when testing both
     // min-width and width.  max-width is only clamped if it is also intrinsic.
     Length logicalWidth = (widthType == MaxSize) ? style().logicalMaxWidth() : style().logicalWidth();
     if (logicalWidth.type() == Intrinsic)
         return true;

     // Children of a horizontal marquee do not fill the container by default.
     // FIXME: Need to deal with MarqueeDirection::Auto value properly. It could be vertical.
     // FIXME: Think about block-flow here.  Need to find out how marquee direction relates to
     // block-flow (as well as how marquee overflow should relate to block flow).
     // https://bugs.webkit.org/show_bug.cgi?id=46472
     if (parent()->isHTMLMarquee()) {
         MarqueeDirection dir = parent()->style().marqueeDirection();
         if (dir == MarqueeDirection::Auto || dir == MarqueeDirection::Forward || dir == MarqueeDirection::Backward || dir == MarqueeDirection::Left || dir == MarqueeDirection::Right)
             return true;
     }

 #if ENABLE(MATHML)
     // RenderMathMLBlocks take the size of their content, not of their container.
     if (parent()->isRenderMathMLBlock())
         return true;
 #endif

     // Flexible box items should shrink wrap, so we lay them out at their intrinsic widths.
     // In the case of columns that have a stretch alignment, we layout at the stretched size
     // to avoid an extra layout when applying alignment.
     if (parent()->isFlexibleBox()) {
         // For multiline columns, we need to apply align-content first, so we can't stretch now.
         if (!parent()->style().isColumnFlexDirection() || parent()->style().flexWrap() != FlexWrap::NoWrap)
             return true;
         if (!columnFlexItemHasStretchAlignment())
             return true;
     }

     // Flexible horizontal boxes lay out children at their intrinsic widths.  Also vertical boxes
     // that don't stretch their kids lay out their children at their intrinsic widths.
     // FIXME: Think about block-flow here.
     // https://bugs.webkit.org/show_bug.cgi?id=46473
     if (parent()->isDeprecatedFlexibleBox() && (parent()->style().boxOrient() == BoxOrient::Horizontal || parent()->style().boxAlign() != BoxAlignment::Stretch))
         return true;

     // Button, input, select, textarea, and legend treat width value of 'auto' as 'intrinsic' unless it's in a
     // stretching column flexbox.
     // FIXME: Think about block-flow here.
     // https://bugs.webkit.org/show_bug.cgi?id=46473
     if (logicalWidth.type() == Auto && !isStretchingColumnFlexItem() && element() && (is<HTMLInputElement>(*element()) || is<HTMLSelectElement>(*element()) || is<HTMLButtonElement>(*element()) || is<HTMLTextAreaElement>(*element()) || is<HTMLLegendElement>(*element())))
         return true;

     if (isHorizontalWritingMode() != containingBlock()->isHorizontalWritingMode())
         return true;

     return false;
 }

 void RenderBox::computeInlineDirectionMargins(const RenderBlock& containingBlock, LayoutUnit containerWidth, LayoutUnit childWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const
 {

     const RenderStyle& containingBlockStyle = containingBlock.style();
     Length marginStartLength = style().marginStartUsing(&containingBlockStyle);
     Length marginEndLength = style().marginEndUsing(&containingBlockStyle);

     if (isFloating() || isInline()) {
         // Inline blocks/tables and floats don't have their margins increased.
         marginStart = minimumValueForLength(marginStartLength, containerWidth);
         marginEnd = minimumValueForLength(marginEndLength, containerWidth);
         return;
     }

     if (containingBlock.isFlexibleBox()) {
         // We need to let flexbox handle the margin adjustment - otherwise, flexbox
         // will think we're wider than we actually are and calculate line sizes
         // wrong. See also http://dev.w3.org/csswg/css-flexbox/#auto-margins
         if (marginStartLength.isAuto())
             marginStartLength = Length(0, Fixed);
         if (marginEndLength.isAuto())
             marginEndLength = Length(0, Fixed);
     }

     // Case One: The object is being centered in the containing block's available logical width.
     if ((marginStartLength.isAuto() && marginEndLength.isAuto() && childWidth < containerWidth)
         || (!marginStartLength.isAuto() && !marginEndLength.isAuto() && containingBlock.style().textAlign() == TextAlignMode::WebKitCenter)) {
         // Other browsers center the margin box for align=center elements so we match them here.
         LayoutUnit marginStartWidth = minimumValueForLength(marginStartLength, containerWidth);
         LayoutUnit marginEndWidth = minimumValueForLength(marginEndLength, containerWidth);
         LayoutUnit centeredMarginBoxStart = std::max<LayoutUnit>(0, (containerWidth - childWidth - marginStartWidth - marginEndWidth) / 2);
         marginStart = centeredMarginBoxStart + marginStartWidth;
         marginEnd = containerWidth - childWidth - marginStart + marginEndWidth;
         return;
     }

     // Case Two: The object is being pushed to the start of the containing block's available logical width.
     if (marginEndLength.isAuto() && childWidth < containerWidth) {
         marginStart = valueForLength(marginStartLength, containerWidth);
         marginEnd = containerWidth - childWidth - marginStart;
         return;
     }

     // Case Three: The object is being pushed to the end of the containing block's available logical width.
     bool pushToEndFromTextAlign = !marginEndLength.isAuto() && ((!containingBlockStyle.isLeftToRightDirection() && containingBlockStyle.textAlign() == TextAlignMode::WebKitLeft)
         || (containingBlockStyle.isLeftToRightDirection() && containingBlockStyle.textAlign() == TextAlignMode::WebKitRight));
     if ((marginStartLength.isAuto() || pushToEndFromTextAlign) && childWidth < containerWidth) {
         marginEnd = valueForLength(marginEndLength, containerWidth);
         marginStart = containerWidth - childWidth - marginEnd;
         return;
     }

     // Case Four: Either no auto margins, or our width is >= the container width (css2.1, 10.3.3).  In that case
     // auto margins will just turn into 0.
     marginStart = minimumValueForLength(marginStartLength, containerWidth);
     marginEnd = minimumValueForLength(marginEndLength, containerWidth);
 }

 RenderBoxFragmentInfo* RenderBox::renderBoxFragmentInfo(RenderFragmentContainer* fragment, RenderBoxFragmentInfoFlags cacheFlag) const
 {
     // Make sure nobody is trying to call this with a null fragment.
     if (!fragment)
         return nullptr;

     // If we have computed our width in this fragment already, it will be cached, and we can
     // just return it.
     RenderBoxFragmentInfo* boxInfo = fragment->renderBoxFragmentInfo(this);
     if (boxInfo && cacheFlag == CacheRenderBoxFragmentInfo)
         return boxInfo;

     return nullptr;
 }

 static bool shouldFlipBeforeAfterMargins(const RenderStyle& containingBlockStyle, const RenderStyle* childStyle)
 {
     ASSERT(containingBlockStyle.isHorizontalWritingMode() != childStyle->isHorizontalWritingMode());
     WritingMode childWritingMode = childStyle->writingMode();
     bool shouldFlip = false;
     switch (containingBlockStyle.writingMode()) {
     case TopToBottomWritingMode:
         shouldFlip = (childWritingMode == RightToLeftWritingMode);
         break;
     case BottomToTopWritingMode:
         shouldFlip = (childWritingMode == RightToLeftWritingMode);
         break;
     case RightToLeftWritingMode:
         shouldFlip = (childWritingMode == BottomToTopWritingMode);
         break;
     case LeftToRightWritingMode:
         shouldFlip = (childWritingMode == BottomToTopWritingMode);
         break;
     }

     if (!containingBlockStyle.isLeftToRightDirection())
         shouldFlip = !shouldFlip;

     return shouldFlip;
 }

 void RenderBox::cacheIntrinsicContentLogicalHeightForFlexItem(LayoutUnit height) const
 {
     if (isFloatingOrOutOfFlowPositioned() || !parent() || !parent()->isFlexibleBox())
         return;
     downcast<RenderFlexibleBox>(parent())->setCachedChildIntrinsicContentLogicalHeight(*this, height);
 }

 void RenderBox::updateLogicalHeight()
 {
     cacheIntrinsicContentLogicalHeightForFlexItem(contentLogicalHeight());
     auto computedValues = computeLogicalHeight(logicalHeight(), logicalTop());
     setLogicalHeight(computedValues.m_extent);
     setLogicalTop(computedValues.m_position);
     setMarginBefore(computedValues.m_margins.m_before);
     setMarginAfter(computedValues.m_margins.m_after);
 }

 RenderBox::LogicalExtentComputedValues RenderBox::computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop) const
 {
     LogicalExtentComputedValues computedValues;
     computedValues.m_extent = logicalHeight;
     computedValues.m_position = logicalTop;

     // Cell height is managed by the table and inline non-replaced elements do not support a height property.
     if (isTableCell() || (isInline() && !isReplaced()))
         return computedValues;

     Length h;
     if (isOutOfFlowPositioned())
         computePositionedLogicalHeight(computedValues);
     else {
         RenderBlock& cb = *containingBlock();
         bool hasPerpendicularContainingBlock = cb.isHorizontalWritingMode() != isHorizontalWritingMode();

         if (!hasPerpendicularContainingBlock) {
             bool shouldFlipBeforeAfter = cb.style().writingMode() != style().writingMode();
             computeBlockDirectionMargins(cb,
                 shouldFlipBeforeAfter ? computedValues.m_margins.m_after : computedValues.m_margins.m_before,
                 shouldFlipBeforeAfter ? computedValues.m_margins.m_before : computedValues.m_margins.m_after);
         }

         // For tables, calculate margins only.
         if (isTable()) {
             if (hasPerpendicularContainingBlock) {
                 bool shouldFlipBeforeAfter = shouldFlipBeforeAfterMargins(cb.style(), &style());
                 computeInlineDirectionMargins(cb, containingBlockLogicalWidthForContent(), computedValues.m_extent,
                     shouldFlipBeforeAfter ? computedValues.m_margins.m_after : computedValues.m_margins.m_before,
                     shouldFlipBeforeAfter ? computedValues.m_margins.m_before : computedValues.m_margins.m_after);
             }
             return computedValues;
         }

         // FIXME: Account for block-flow in flexible boxes.
         // https://bugs.webkit.org/show_bug.cgi?id=46418
         bool inHorizontalBox = parent()->isDeprecatedFlexibleBox() && parent()->style().boxOrient() == BoxOrient::Horizontal;
         bool stretching = parent()->style().boxAlign() == BoxAlignment::Stretch;
         bool treatAsReplaced = shouldComputeSizeAsReplaced() && (!inHorizontalBox || !stretching);
         bool checkMinMaxHeight = false;

         // The parent box is flexing us, so it has increased or decreased our height.  We have to
         // grab our cached flexible height.
         // FIXME: Account for block-flow in flexible boxes.
         // https://bugs.webkit.org/show_bug.cgi?id=46418
         if (hasOverrideContentLogicalHeight() && (parent()->isFlexibleBoxIncludingDeprecated() || parent()->isRenderGrid())) {
             h = Length(overrideContentLogicalHeight(), Fixed);
         } else if (treatAsReplaced)
             h = Length(computeReplacedLogicalHeight(), Fixed);
         else {
             h = style().logicalHeight();
             checkMinMaxHeight = true;
         }

         // Block children of horizontal flexible boxes fill the height of the box.
         // FIXME: Account for block-flow in flexible boxes.
         // https://bugs.webkit.org/show_bug.cgi?id=46418
         if (h.isAuto() && is<RenderDeprecatedFlexibleBox>(*parent()) && parent()->style().boxOrient() == BoxOrient::Horizontal
                 && downcast<RenderDeprecatedFlexibleBox>(*parent()).isStretchingChildren()) {
             h = Length(parentBox()->contentLogicalHeight() - marginBefore() - marginAfter() - borderAndPaddingLogicalHeight(), Fixed);
             checkMinMaxHeight = false;
         }

         LayoutUnit heightResult;
         if (checkMinMaxHeight) {
             LayoutUnit intrinsicHeight = computedValues.m_extent - borderAndPaddingLogicalHeight();
             heightResult = computeLogicalHeightUsing(MainOrPreferredSize, style().logicalHeight(), intrinsicHeight).valueOr(computedValues.m_extent);
             heightResult = constrainLogicalHeightByMinMax(heightResult, intrinsicHeight);
         } else {
             // The only times we don't check min/max height are when a fixed length has
             // been given as an override.  Just use that.  The value has already been adjusted
             // for box-sizing.
             ASSERT(h.isFixed());
             heightResult = h.value() + borderAndPaddingLogicalHeight();
         }

         computedValues.m_extent = heightResult;

         if (hasPerpendicularContainingBlock) {
             bool shouldFlipBeforeAfter = shouldFlipBeforeAfterMargins(cb.style(), &style());
             computeInlineDirectionMargins(cb, containingBlockLogicalWidthForContent(), heightResult,
                     shouldFlipBeforeAfter ? computedValues.m_margins.m_after : computedValues.m_margins.m_before,
                     shouldFlipBeforeAfter ? computedValues.m_margins.m_before : computedValues.m_margins.m_after);
         }
     }

     // WinIE quirk: The <html> block always fills the entire canvas in quirks mode.  The <body> always fills the
     // <html> block in quirks mode.  Only apply this quirk if the block is normal flow and no height
     // is specified. When we're printing, we also need this quirk if the body or root has a percentage
     // height since we don't set a height in RenderView when we're printing. So without this quirk, the
     // height has nothing to be a percentage of, and it ends up being 0. That is bad.
     bool paginatedContentNeedsBaseHeight = document().printing() && h.isPercentOrCalculated()
         && (isDocumentElementRenderer() || (isBody() && document().documentElement()->renderer()->style().logicalHeight().isPercentOrCalculated())) && !isInline();
     if (stretchesToViewport() || paginatedContentNeedsBaseHeight) {
         LayoutUnit margins = collapsedMarginBefore() + collapsedMarginAfter();
         LayoutUnit visibleHeight = view().pageOrViewLogicalHeight();
         if (isDocumentElementRenderer())
             computedValues.m_extent = std::max(computedValues.m_extent, visibleHeight - margins);
         else {
             LayoutUnit marginsBordersPadding = margins + parentBox()->marginBefore() + parentBox()->marginAfter() + parentBox()->borderAndPaddingLogicalHeight();
             computedValues.m_extent = std::max(computedValues.m_extent, visibleHeight - marginsBordersPadding);
         }
     }
     return computedValues;
 }

 LayoutUnit RenderBox::computeLogicalHeightWithoutLayout() const
 {
     // FIXME:: We should probably return something other than just
     // border + padding, but for now we have no good way to do anything else
     // without layout, so we just use that.
     LogicalExtentComputedValues computedValues = computeLogicalHeight(borderAndPaddingLogicalHeight(), 0_lu);
     return computedValues.m_extent;
 }

 Optional<LayoutUnit> RenderBox::computeLogicalHeightUsing(SizeType heightType, const Length& height, Optional<LayoutUnit> intrinsicContentHeight) const
 {
     if (Optional<LayoutUnit> logicalHeight = computeContentAndScrollbarLogicalHeightUsing(heightType, height, intrinsicContentHeight))
         return adjustBorderBoxLogicalHeightForBoxSizing(logicalHeight.value());
     return WTF::nullopt;
 }

 Optional<LayoutUnit> RenderBox::computeContentLogicalHeight(SizeType heightType, const Length& height, Optional<LayoutUnit> intrinsicContentHeight) const
 {
     if (Optional<LayoutUnit> heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(heightType, height, intrinsicContentHeight))
         return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());
     return WTF::nullopt;
 }

 Optional<LayoutUnit> RenderBox::computeIntrinsicLogicalContentHeightUsing(Length logicalHeightLength, Optional<LayoutUnit> intrinsicContentHeight, LayoutUnit borderAndPadding) const
 {
     // FIXME: The CSS sizing spec is considering changing what min-content/max-content should resolve to.
     // If that happens, this code will have to change.
     if (logicalHeightLength.isMinContent() || logicalHeightLength.isMaxContent() || logicalHeightLength.isFitContent()) {
         if (!intrinsicContentHeight)
             return intrinsicContentHeight;
         if (style().boxSizing() == BoxSizing::BorderBox)
             return intrinsicContentHeight.value() + borderAndPaddingLogicalHeight();
         return intrinsicContentHeight;
     }
     if (logicalHeightLength.isFillAvailable())
         return containingBlock()->availableLogicalHeight(ExcludeMarginBorderPadding) - borderAndPadding;
     ASSERT_NOT_REACHED();
     return 0_lu;
 }

 Optional<LayoutUnit> RenderBox::computeContentAndScrollbarLogicalHeightUsing(SizeType heightType, const Length& height, Optional<LayoutUnit> intrinsicContentHeight) const
 {
     if (height.isAuto())
         return heightType == MinSize ? Optional<LayoutUnit>(0) : WTF::nullopt;
     // FIXME: The CSS sizing spec is considering changing what min-content/max-content should resolve to.
     // If that happens, this code will have to change.
     if (height.isIntrinsic())
         return computeIntrinsicLogicalContentHeightUsing(height, intrinsicContentHeight, borderAndPaddingLogicalHeight());
     if (height.isFixed())
         return LayoutUnit(height.value());
     if (height.isPercentOrCalculated())
         return computePercentageLogicalHeight(height);
     return WTF::nullopt;
 }

 bool RenderBox::skipContainingBlockForPercentHeightCalculation(const RenderBox& containingBlock, bool isPerpendicularWritingMode) const
 {
     // Flow threads for multicol or paged overflow should be skipped. They are invisible to the DOM,
     // and percent heights of children should be resolved against the multicol or paged container.
     if (containingBlock.isInFlowRenderFragmentedFlow() && !isPerpendicularWritingMode)
         return true;

     // Render view is not considered auto height.
     if (is<RenderView>(containingBlock))
         return false;

     // If the writing mode of the containing block is orthogonal to ours, it means
     // that we shouldn't skip anything, since we're going to resolve the
     // percentage height against a containing block *width*.
     if (isPerpendicularWritingMode)
         return false;

     // Anonymous blocks should not impede percentage resolution on a child.
     // Examples of such anonymous blocks are blocks wrapped around inlines that
     // have block siblings (from the CSS spec) and multicol flow threads (an
     // implementation detail). Another implementation detail, ruby runs, create
     // anonymous inline-blocks, so skip those too. All other types of anonymous
     // objects, such as table-cells and flexboxes, will be treated as if they were
     // non-anonymous.
     if (containingBlock.isAnonymous())
         return containingBlock.style().display() == DisplayType::Block || containingBlock.style().display() == DisplayType::InlineBlock;

     // For quirks mode, we skip most auto-height containing blocks when computing
     // percentages.
     return document().inQuirksMode() && !containingBlock.isTableCell() && !containingBlock.isOutOfFlowPositioned() && !containingBlock.isRenderGrid() && containingBlock.style().logicalHeight().isAuto();
 }

 bool RenderBox::shouldTreatChildAsReplacedInTableCells() const
 {
     if (isReplaced())
         return true;
     return element() && (element()->isFormControlElement() || is<HTMLImageElement>(element()));
 }

 static bool tableCellShouldHaveZeroInitialSize(const RenderBlock& block, const RenderBox& child, bool scrollsOverflowY)
 {
     // Normally we would let the cell size intrinsically, but scrolling overflow has to be
     // treated differently, since WinIE lets scrolled overflow fragments shrink as needed.
     // While we can't get all cases right, we can at least detect when the cell has a specified
     // height or when the table has a specified height. In these cases we want to initially have
     // no size and allow the flexing of the table or the cell to its specified height to cause us
     // to grow to fill the space. This could end up being wrong in some cases, but it is
     // preferable to the alternative (sizing intrinsically and making the row end up too big).
     const RenderTableCell& cell = downcast<RenderTableCell>(block);
     return scrollsOverflowY && !child.shouldTreatChildAsReplacedInTableCells() && (!cell.style().logicalHeight().isAuto() || !cell.table()->style().logicalHeight().isAuto());
 }

 Optional<LayoutUnit> RenderBox::computePercentageLogicalHeight(const Length& height) const
 {
     Optional<LayoutUnit> availableHeight;

     bool skippedAutoHeightContainingBlock = false;
     RenderBlock* cb = containingBlock();
     const RenderBox* containingBlockChild = this;
     LayoutUnit rootMarginBorderPaddingHeight;
     bool isHorizontal = isHorizontalWritingMode();
     while (cb && !is<RenderView>(*cb) && skipContainingBlockForPercentHeightCalculation(*cb, isHorizontal != cb->isHorizontalWritingMode())) {
         if (cb->isBody() || cb->isDocumentElementRenderer())
             rootMarginBorderPaddingHeight += cb->marginBefore() + cb->marginAfter() + cb->borderAndPaddingLogicalHeight();
         skippedAutoHeightContainingBlock = true;
         containingBlockChild = cb;
         cb = cb->containingBlock();
     }
     cb->addPercentHeightDescendant(const_cast<RenderBox&>(*this));

     if (isHorizontal != cb->isHorizontalWritingMode())
         availableHeight = containingBlockChild->containingBlockLogicalWidthForContent();
     else if (hasOverrideContainingBlockContentLogicalHeight())
         availableHeight = overrideContainingBlockContentLogicalHeight();
     else if (is<RenderTableCell>(*cb)) {
         if (!skippedAutoHeightContainingBlock) {
             // Table cells violate what the CSS spec says to do with heights. Basically we
             // don't care if the cell specified a height or not. We just always make ourselves
             // be a percentage of the cell's current content height.
             if (!cb->hasOverrideContentLogicalHeight())
                 return tableCellShouldHaveZeroInitialSize(*cb, *this, scrollsOverflowY()) ? Optional<LayoutUnit>(0) : WTF::nullopt;

             availableHeight = cb->overrideContentLogicalHeight();
         }
     } else
         availableHeight = cb->availableLogicalHeightForPercentageComputation();

     if (!availableHeight)
         return availableHeight;

     LayoutUnit result = valueForLength(height, availableHeight.value() - rootMarginBorderPaddingHeight + (isTable() && isOutOfFlowPositioned() ? cb->paddingBefore() + cb->paddingAfter() : 0_lu));

     // |overrideContentLogicalHeight| is the maximum height made available by the
     // cell to its percent height children when we decide they can determine the
     // height of the cell. If the percent height child is box-sizing:content-box
     // then we must subtract the border and padding from the cell's
     // |availableHeight| (given by |overrideContentLogicalHeight|) to arrive
     // at the child's computed height.
     bool subtractBorderAndPadding = isTable() || (is<RenderTableCell>(*cb) && !skippedAutoHeightContainingBlock && cb->hasOverrideContentLogicalHeight());
     if (subtractBorderAndPadding) {
         result -= borderAndPaddingLogicalHeight();
         return std::max(0_lu, result);
     }
     return result;
 }

 LayoutUnit RenderBox::computeReplacedLogicalWidth(ShouldComputePreferred shouldComputePreferred) const
 {
     return computeReplacedLogicalWidthRespectingMinMaxWidth(computeReplacedLogicalWidthUsing(MainOrPreferredSize, style().logicalWidth()), shouldComputePreferred);
 }

 LayoutUnit RenderBox::computeReplacedLogicalWidthRespectingMinMaxWidth(LayoutUnit logicalWidth, ShouldComputePreferred shouldComputePreferred) const
 {
     auto& logicalMinWidth = style().logicalMinWidth();
     auto& logicalMaxWidth = style().logicalMaxWidth();
     bool useLogicalWidthForMinWidth = (shouldComputePreferred == ComputePreferred && logicalMinWidth.isPercentOrCalculated()) || logicalMinWidth.isUndefined();
     bool useLogicalWidthForMaxWidth = (shouldComputePreferred == ComputePreferred && logicalMaxWidth.isPercentOrCalculated()) || logicalMaxWidth.isUndefined();
     auto minLogicalWidth =  useLogicalWidthForMinWidth ? logicalWidth : computeReplacedLogicalWidthUsing(MinSize, logicalMinWidth);
     auto maxLogicalWidth =  useLogicalWidthForMaxWidth ? logicalWidth : computeReplacedLogicalWidthUsing(MaxSize, logicalMaxWidth);
     return std::max(minLogicalWidth, std::min(logicalWidth, maxLogicalWidth));
 }

 LayoutUnit RenderBox::computeReplacedLogicalWidthUsing(SizeType widthType, Length logicalWidth) const
 {
     ASSERT(widthType == MinSize || widthType == MainOrPreferredSize || !logicalWidth.isAuto());
     if (widthType == MinSize && logicalWidth.isAuto())
         return adjustContentBoxLogicalWidthForBoxSizing(0);

     switch (logicalWidth.type()) {
         case Fixed:
             return adjustContentBoxLogicalWidthForBoxSizing(logicalWidth.value());
         case MinContent:
         case MaxContent: {
             // MinContent/MaxContent don't need the availableLogicalWidth argument.
             LayoutUnit availableLogicalWidth;
             return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
         }
         case FitContent:
         case FillAvailable:
         case Percent:
         case Calculated: {
             // FIXME: containingBlockLogicalWidthForContent() is wrong if the replaced element's block-flow is perpendicular to the
             // containing block's block-flow.
             // https://bugs.webkit.org/show_bug.cgi?id=46496
             const LayoutUnit cw = isOutOfFlowPositioned() ? containingBlockLogicalWidthForPositioned(downcast<RenderBoxModelObject>(*container())) : containingBlockLogicalWidthForContent();
             Length containerLogicalWidth = containingBlock()->style().logicalWidth();
             // FIXME: Handle cases when containing block width is calculated or viewport percent.
             // https://bugs.webkit.org/show_bug.cgi?id=91071
             if (logicalWidth.isIntrinsic())
                 return computeIntrinsicLogicalWidthUsing(logicalWidth, cw, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
             if (cw > 0 || (!cw && (containerLogicalWidth.isFixed() || containerLogicalWidth.isPercentOrCalculated())))
                 return adjustContentBoxLogicalWidthForBoxSizing(minimumValueForLength(logicalWidth, cw));
             return 0_lu;
         }
         case Intrinsic:
         case MinIntrinsic:
         case Auto:
         case Relative:
         case Undefined:
             return intrinsicLogicalWidth();
     }

     ASSERT_NOT_REACHED();
     return 0;
 }

 LayoutUnit RenderBox::computeReplacedLogicalHeight(Optional<LayoutUnit>) const
 {
     return computeReplacedLogicalHeightRespectingMinMaxHeight(computeReplacedLogicalHeightUsing(MainOrPreferredSize, style().logicalHeight()));
 }

 static bool allowMinMaxPercentagesInAutoHeightBlocksQuirk()
 {
 #if PLATFORM(MAC)
     return MacApplication::isIBooks();
 #elif PLATFORM(IOS_FAMILY)
     return IOSApplication::isIBooks();
 #endif
     return false;
 }

 bool RenderBox::replacedMinMaxLogicalHeightComputesAsNone(SizeType sizeType) const
 {
     ASSERT(sizeType == MinSize || sizeType == MaxSize);

     auto logicalHeight = sizeType == MinSize ? style().logicalMinHeight() : style().logicalMaxHeight();
     auto initialLogicalHeight = sizeType == MinSize ? RenderStyle::initialMinSize() : RenderStyle::initialMaxSize();

     if (logicalHeight == initialLogicalHeight)
         return true;

     // Make sure % min-height and % max-height resolve to none if the containing block has auto height.
     // Note that the "height" case for replaced elements was handled by hasReplacedLogicalHeight, which is why
     // min and max-height are the only ones handled here.
     // FIXME: For now we put in a quirk for iBooks until we can move them to viewport units.
     if (auto* cb = containingBlockForAutoHeightDetection(logicalHeight))
         return allowMinMaxPercentagesInAutoHeightBlocksQuirk() ? false : cb->hasAutoHeightOrContainingBlockWithAutoHeight();

     return false;
 }

 LayoutUnit RenderBox::computeReplacedLogicalHeightRespectingMinMaxHeight(LayoutUnit logicalHeight) const
 {
     LayoutUnit minLogicalHeight;
     if (!replacedMinMaxLogicalHeightComputesAsNone(MinSize))
         minLogicalHeight = computeReplacedLogicalHeightUsing(MinSize, style().logicalMinHeight());
     LayoutUnit maxLogicalHeight = logicalHeight;
     if (!replacedMinMaxLogicalHeightComputesAsNone(MaxSize))
         maxLogicalHeight = computeReplacedLogicalHeightUsing(MaxSize, style().logicalMaxHeight());
     return std::max(minLogicalHeight, std::min(logicalHeight, maxLogicalHeight));
 }

 LayoutUnit RenderBox::computeReplacedLogicalHeightUsing(SizeType heightType, Length logicalHeight) const
 {
     ASSERT(heightType == MinSize || heightType == MainOrPreferredSize || !logicalHeight.isAuto());
     if (heightType == MinSize && logicalHeight.isAuto())
         return adjustContentBoxLogicalHeightForBoxSizing(Optional<LayoutUnit>(0));

     switch (logicalHeight.type()) {
         case Fixed:
             return adjustContentBoxLogicalHeightForBoxSizing(LayoutUnit(logicalHeight.value()));
         case Percent:
         case Calculated:
         {
             auto* container = isOutOfFlowPositioned() ? this->container() : containingBlock();
             while (container && container->isAnonymous()) {
                 // Stop at rendering context root.
                 if (is<RenderView>(*container))
                     break;
                 container = container->containingBlock();
             }
             Optional<LayoutUnit> stretchedHeight;
             if (is<RenderBlock>(container)) {
                 auto* block = downcast<RenderBlock>(container);
                 block->addPercentHeightDescendant(*const_cast<RenderBox*>(this));
                 if (block->isFlexItem())
                     stretchedHeight = downcast<RenderFlexibleBox>(block->parent())->childLogicalHeightForPercentageResolution(*block);
                 else if (block->isGridItem() && block->hasOverrideContentLogicalHeight())
                     stretchedHeight = block->overrideContentLogicalHeight();
             }

             // FIXME: This calculation is not patched for block-flow yet.
             // https://bugs.webkit.org/show_bug.cgi?id=46500
             if (container->isOutOfFlowPositioned()
                 && container->style().height().isAuto()
                 && !(container->style().top().isAuto() || container->style().bottom().isAuto())) {
                 ASSERT_WITH_SECURITY_IMPLICATION(container->isRenderBlock());
                 auto& block = downcast<RenderBlock>(*container);
                 auto computedValues = block.computeLogicalHeight(block.logicalHeight(), 0);
                 LayoutUnit newContentHeight = computedValues.m_extent - block.borderAndPaddingLogicalHeight() - block.scrollbarLogicalHeight();
                 return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeight, newContentHeight));
             }

             // FIXME: availableLogicalHeight() is wrong if the replaced element's block-flow is perpendicular to the
             // containing block's block-flow.
             // https://bugs.webkit.org/show_bug.cgi?id=46496
             LayoutUnit availableHeight;
             if (isOutOfFlowPositioned())
                 availableHeight = containingBlockLogicalHeightForPositioned(downcast<RenderBoxModelObject>(*container));
             else if (stretchedHeight)
                 availableHeight = stretchedHeight.value();
             else {
                 availableHeight = containingBlockLogicalHeightForContent(IncludeMarginBorderPadding);
                 // It is necessary to use the border-box to match WinIE's broken
                 // box model.  This is essential for sizing inside
                 // table cells using percentage heights.
                 // FIXME: This needs to be made block-flow-aware.  If the cell and image are perpendicular block-flows, this isn't right.
                 // https://bugs.webkit.org/show_bug.cgi?id=46997
                 while (container && !is<RenderView>(*container)
                     && (container->style().logicalHeight().isAuto() || container->style().logicalHeight().isPercentOrCalculated())) {
                     if (container->isTableCell()) {
                         // Don't let table cells squeeze percent-height replaced elements
                         // <http://bugs.webkit.org/show_bug.cgi?id=15359>
                         availableHeight = std::max(availableHeight, intrinsicLogicalHeight());
                         return valueForLength(logicalHeight, availableHeight - borderAndPaddingLogicalHeight());
                     }
                     downcast<RenderBlock>(*container).addPercentHeightDescendant(const_cast<RenderBox&>(*this));
                     container = container->containingBlock();
                 }
             }
             return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeight, availableHeight));
         }
         case MinContent:
         case MaxContent:
         case FitContent:
         case FillAvailable:
             return adjustContentBoxLogicalHeightForBoxSizing(computeIntrinsicLogicalContentHeightUsing(logicalHeight, intrinsicLogicalHeight(), borderAndPaddingLogicalHeight()));
         default:
             return intrinsicLogicalHeight();
     }
 }

 LayoutUnit RenderBox::availableLogicalHeight(AvailableLogicalHeightType heightType) const
 {
     return constrainLogicalHeightByMinMax(availableLogicalHeightUsing(style().logicalHeight(), heightType), WTF::nullopt);
 }

 LayoutUnit RenderBox::availableLogicalHeightUsing(const Length& h, AvailableLogicalHeightType heightType) const
 {
     // We need to stop here, since we don't want to increase the height of the table
     // artificially.  We're going to rely on this cell getting expanded to some new
     // height, and then when we lay out again we'll use the calculation below.
     if (isTableCell() && (h.isAuto() || h.isPercentOrCalculated())) {
         if (hasOverrideContentLogicalHeight())
             return overrideContentLogicalHeight();
         return logicalHeight() - borderAndPaddingLogicalHeight();
     }

     if (isFlexItem()) {
         auto& flexBox = downcast<RenderFlexibleBox>(*parent());
         auto stretchedHeight = flexBox.childLogicalHeightForPercentageResolution(*this);
         if (stretchedHeight)
             return stretchedHeight.value();
     }

     if (h.isPercentOrCalculated() && isOutOfFlowPositioned() && !isRenderFragmentedFlow()) {
         // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
         LayoutUnit availableHeight = containingBlockLogicalHeightForPositioned(*containingBlock());
         return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(h, availableHeight));
     }

     if (Optional<LayoutUnit> heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(MainOrPreferredSize, h, WTF::nullopt))
         return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());

     // FIXME: Check logicalTop/logicalBottom here to correctly handle vertical writing-mode.
     // https://bugs.webkit.org/show_bug.cgi?id=46500
     if (is<RenderBlock>(*this) && isOutOfFlowPositioned() && style().height().isAuto() && !(style().top().isAuto() || style().bottom().isAuto())) {
         RenderBlock& block = const_cast<RenderBlock&>(downcast<RenderBlock>(*this));
         auto computedValues = block.computeLogicalHeight(block.logicalHeight(), 0);
         return computedValues.m_extent - block.borderAndPaddingLogicalHeight() - block.scrollbarLogicalHeight();
     }

     // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
     LayoutUnit availableHeight = containingBlockLogicalHeightForContent(heightType);
     if (heightType == ExcludeMarginBorderPadding) {
         // FIXME: Margin collapsing hasn't happened yet, so this incorrectly removes collapsed margins.
         availableHeight -= marginBefore() + marginAfter() + borderAndPaddingLogicalHeight();
     }
     return availableHeight;
 }

 void RenderBox::computeBlockDirectionMargins(const RenderBlock& containingBlock, LayoutUnit& marginBefore, LayoutUnit& marginAfter) const
 {
     if (isTableCell()) {
         // FIXME: Not right if we allow cells to have different directionality than the table.  If we do allow this, though,
         // we may just do it with an extra anonymous block inside the cell.
         marginBefore = 0;
         marginAfter = 0;
         return;
     }

     // Margins are calculated with respect to the logical width of
     // the containing block (8.3)
     LayoutUnit cw = containingBlockLogicalWidthForContent();
     const RenderStyle& containingBlockStyle = containingBlock.style();
     marginBefore = minimumValueForLength(style().marginBeforeUsing(&containingBlockStyle), cw);
     marginAfter = minimumValueForLength(style().marginAfterUsing(&containingBlockStyle), cw);
 }

 void RenderBox::computeAndSetBlockDirectionMargins(const RenderBlock& containingBlock)
 {
     LayoutUnit marginBefore;
     LayoutUnit marginAfter;
     computeBlockDirectionMargins(containingBlock, marginBefore, marginAfter);
     containingBlock.setMarginBeforeForChild(*this, marginBefore);
     containingBlock.setMarginAfterForChild(*this, marginAfter);
 }

 LayoutUnit RenderBox::containingBlockLogicalWidthForPositioned(const RenderBoxModelObject& containingBlock, RenderFragmentContainer* fragment, bool checkForPerpendicularWritingMode) const
 {
     if (checkForPerpendicularWritingMode && containingBlock.isHorizontalWritingMode() != isHorizontalWritingMode())
         return containingBlockLogicalHeightForPositioned(containingBlock, false);

     if (hasOverrideContainingBlockContentLogicalWidth()) {
         if (auto overrideLogicalWidth = overrideContainingBlockContentLogicalWidth())
             return overrideLogicalWidth.value();
     }

     if (is<RenderBox>(containingBlock)) {
         bool isFixedPosition = isFixedPositioned();

         RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
         if (!fragmentedFlow) {
             if (isFixedPosition && is<RenderView>(containingBlock))
                 return downcast<RenderView>(containingBlock).clientLogicalWidthForFixedPosition();

             return downcast<RenderBox>(containingBlock).clientLogicalWidth();
         }

         if (!is<RenderBlock>(containingBlock))
             return downcast<RenderBox>(containingBlock).clientLogicalWidth();

         const RenderBlock& cb = downcast<RenderBlock>(containingBlock);
         RenderBoxFragmentInfo* boxInfo = nullptr;
         if (!fragment) {
             if (is<RenderFragmentedFlow>(containingBlock) && !checkForPerpendicularWritingMode)
                 return downcast<RenderFragmentedFlow>(containingBlock).contentLogicalWidthOfFirstFragment();
             if (isWritingModeRoot()) {
                 LayoutUnit cbPageOffset = cb.offsetFromLogicalTopOfFirstPage();
                 RenderFragmentContainer* cbFragment = cb.fragmentAtBlockOffset(cbPageOffset);
                 if (cbFragment)
                     boxInfo = cb.renderBoxFragmentInfo(cbFragment);
             }
         } else if (fragmentedFlow->isHorizontalWritingMode() == containingBlock.isHorizontalWritingMode()) {
             RenderFragmentContainer* containingBlockFragment = cb.clampToStartAndEndFragments(fragment);
             boxInfo = cb.renderBoxFragmentInfo(containingBlockFragment);
         }
         return (boxInfo) ? std::max<LayoutUnit>(0, cb.clientLogicalWidth() - (cb.logicalWidth() - boxInfo->logicalWidth())) : cb.clientLogicalWidth();
     }

     ASSERT(containingBlock.isInFlowPositioned());

     const auto& flow = downcast<RenderInline>(containingBlock);
     InlineFlowBox* first = flow.firstLineBox();
     InlineFlowBox* last = flow.lastLineBox();

     // If the containing block is empty, return a width of 0.
     if (!first || !last)
         return 0;

     LayoutUnit fromLeft;
     LayoutUnit fromRight;
     if (containingBlock.style().isLeftToRightDirection()) {
         fromLeft = first->logicalLeft() + first->borderLogicalLeft();
         fromRight = last->logicalLeft() + last->logicalWidth() - last->borderLogicalRight();
     } else {
         fromRight = first->logicalLeft() + first->logicalWidth() - first->borderLogicalRight();
         fromLeft = last->logicalLeft() + last->borderLogicalLeft();
     }

     return std::max<LayoutUnit>(0, fromRight - fromLeft);
 }

 LayoutUnit RenderBox::containingBlockLogicalHeightForPositioned(const RenderBoxModelObject& containingBlock, bool checkForPerpendicularWritingMode) const
 {
     if (checkForPerpendicularWritingMode && containingBlock.isHorizontalWritingMode() != isHorizontalWritingMode())
         return containingBlockLogicalWidthForPositioned(containingBlock, nullptr, false);

     if (hasOverrideContainingBlockContentLogicalHeight()) {
         if (auto overrideLogicalHeight = overrideContainingBlockContentLogicalHeight())
             return overrideLogicalHeight.value();
     }

     if (containingBlock.isBox()) {
         bool isFixedPosition = isFixedPositioned();

         if (isFixedPosition && is<RenderView>(containingBlock))
             return downcast<RenderView>(containingBlock).clientLogicalHeightForFixedPosition();

         const RenderBlock& cb = is<RenderBlock>(containingBlock) ? downcast<RenderBlock>(containingBlock) : *containingBlock.containingBlock();
         LayoutUnit result = cb.clientLogicalHeight();
         RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
         if (fragmentedFlow && is<RenderFragmentedFlow>(containingBlock) && fragmentedFlow->isHorizontalWritingMode() == containingBlock.isHorizontalWritingMode())
             return downcast<RenderFragmentedFlow>(containingBlock).contentLogicalHeightOfFirstFragment();
         return result;
     }

     ASSERT(containingBlock.isInFlowPositioned());

     const auto& flow = downcast<RenderInline>(containingBlock);
     InlineFlowBox* first = flow.firstLineBox();
     InlineFlowBox* last = flow.lastLineBox();

     // If the containing block is empty, return a height of 0.
     if (!first || !last)
         return 0;

     LayoutUnit heightResult;
     LayoutRect boundingBox = flow.linesBoundingBox();
     if (containingBlock.isHorizontalWritingMode())
         heightResult = boundingBox.height();
     else
         heightResult = boundingBox.width();
     heightResult -= (containingBlock.borderBefore() + containingBlock.borderAfter());
     return heightResult;
 }

 static void computeInlineStaticDistance(Length& logicalLeft, Length& logicalRight, const RenderBox* child, const RenderBoxModelObject& containerBlock, LayoutUnit containerLogicalWidth, RenderFragmentContainer* fragment)
 {
     if (!logicalLeft.isAuto() || !logicalRight.isAuto())
         return;

     RenderObject* parent = child->parent();
     TextDirection parentDirection = parent->style().direction();

     // This method is using enclosingBox() which is wrong for absolutely
     // positioned grid items, as they rely on the grid area. So for grid items if
     // both "left" and "right" properties are "auto", we can consider that one of
     // them (depending on the direction) is simply "0".
     if (parent->isRenderGrid() && parent == child->containingBlock()) {
         if (parentDirection == TextDirection::LTR)
             logicalLeft.setValue(Fixed, 0);
         else
             logicalRight.setValue(Fixed, 0);
         return;
     }

     // FIXME: The static distance computation has not been patched for mixed writing modes yet.
     if (parentDirection == TextDirection::LTR) {
         LayoutUnit staticPosition = child->layer()->staticInlinePosition() - containerBlock.borderLogicalLeft();
         for (auto* current = parent; current && current != &containerBlock; current = current->container()) {
             if (!is<RenderBox>(*current))
                 continue;
             const auto& renderBox = downcast<RenderBox>(*current);
             staticPosition += renderBox.logicalLeft();
             if (renderBox.isInFlowPositioned())
                 staticPosition += renderBox.isHorizontalWritingMode() ? renderBox.offsetForInFlowPosition().width() : renderBox.offsetForInFlowPosition().height();
             if (fragment && is<RenderBlock>(*current)) {
                 const RenderBlock& currentBlock = downcast<RenderBlock>(*current);
                 fragment = currentBlock.clampToStartAndEndFragments(fragment);
                 RenderBoxFragmentInfo* boxInfo = currentBlock.renderBoxFragmentInfo(fragment);
                 if (boxInfo)
                     staticPosition += boxInfo->logicalLeft();
             }
         }
         logicalLeft.setValue(Fixed, staticPosition);
     } else {
         LayoutUnit staticPosition = child->layer()->staticInlinePosition() + containerLogicalWidth + containerBlock.borderLogicalLeft();
         auto& enclosingBox = parent->enclosingBox();
         if (&enclosingBox != &containerBlock && containerBlock.isDescendantOf(&enclosingBox)) {
             logicalRight.setValue(Fixed, staticPosition);
             return;
         }

         staticPosition -= enclosingBox.logicalWidth();
         for (const RenderElement* current = &enclosingBox; current; current = current->container()) {
             if (!is<RenderBox>(*current))
                 continue;

             if (current != &containerBlock) {
                 auto& renderBox = downcast<RenderBox>(*current);
                 staticPosition -= renderBox.logicalLeft();
                 if (renderBox.isInFlowPositioned())
                     staticPosition -= renderBox.isHorizontalWritingMode() ? renderBox.offsetForInFlowPosition().width() : renderBox.offsetForInFlowPosition().height();
             }
             if (fragment && is<RenderBlock>(*current)) {
                 auto& currentBlock = downcast<RenderBlock>(*current);
                 fragment = currentBlock.clampToStartAndEndFragments(fragment);
                 RenderBoxFragmentInfo* boxInfo = currentBlock.renderBoxFragmentInfo(fragment);
                 if (boxInfo) {
                     if (current != &containerBlock)
                         staticPosition -= currentBlock.logicalWidth() - (boxInfo->logicalLeft() + boxInfo->logicalWidth());
                     if (current == &enclosingBox)
                         staticPosition += enclosingBox.logicalWidth() - boxInfo->logicalWidth();
                 }
             }
             if (current == &containerBlock)
                 break;
         }
         logicalRight.setValue(Fixed, staticPosition);
     }
 }

 void RenderBox::computePositionedLogicalWidth(LogicalExtentComputedValues& computedValues, RenderFragmentContainer* fragment) const
 {
     if (isReplaced()) {
         // FIXME: Positioned replaced elements inside a flow thread are not working properly
         // with variable width fragments (see https://bugs.webkit.org/show_bug.cgi?id=69896 ).
         computePositionedLogicalWidthReplaced(computedValues);
         return;
     }

     // QUESTIONS
     // FIXME 1: Should we still deal with these the cases of 'left' or 'right' having
     // the type 'static' in determining whether to calculate the static distance?
     // NOTE: 'static' is not a legal value for 'left' or 'right' as of CSS 2.1.

     // FIXME 2: Can perhaps optimize out cases when max-width/min-width are greater
     // than or less than the computed width().  Be careful of box-sizing and
     // percentage issues.

     // The following is based off of the W3C Working Draft from April 11, 2006 of
     // CSS 2.1: Section 10.3.7 "Absolutely positioned, non-replaced elements"
     // <http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width>
     // (block-style-comments in this function and in computePositionedLogicalWidthUsing()
     // correspond to text from the spec)


     // We don't use containingBlock(), since we may be positioned by an enclosing
     // relative positioned inline.
     const RenderBoxModelObject& containerBlock = downcast<RenderBoxModelObject>(*container());

     const LayoutUnit containerLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, fragment);

     // Use the container block's direction except when calculating the static distance
     // This conforms with the reference results for abspos-replaced-width-margin-000.htm
     // of the CSS 2.1 test suite
     TextDirection containerDirection = containerBlock.style().direction();

     bool isHorizontal = isHorizontalWritingMode();
     const LayoutUnit bordersPlusPadding = borderAndPaddingLogicalWidth();
     const Length marginLogicalLeft = isHorizontal ? style().marginLeft() : style().marginTop();
     const Length marginLogicalRight = isHorizontal ? style().marginRight() : style().marginBottom();

     Length logicalLeftLength = style().logicalLeft();
     Length logicalRightLength = style().logicalRight();

     /*---------------------------------------------------------------------------*\
      * For the purposes of this section and the next, the term "static position"
      * (of an element) refers, roughly, to the position an element would have had
      * in the normal flow. More precisely:
      *
      * * The static position for 'left' is the distance from the left edge of the
      *   containing block to the left margin edge of a hypothetical box that would
      *   have been the first box of the element if its 'position' property had
      *   been 'static' and 'float' had been 'none'. The value is negative if the
      *   hypothetical box is to the left of the containing block.
      * * The static position for 'right' is the distance from the right edge of the
      *   containing block to the right margin edge of the same hypothetical box as
      *   above. The value is positive if the hypothetical box is to the left of the
      *   containing block's edge.
      *
      * But rather than actually calculating the dimensions of that hypothetical box,
      * user agents are free to make a guess at its probable position.
      *
      * For the purposes of calculating the static position, the containing block of
      * fixed positioned elements is the initial containing block instead of the
      * viewport, and all scrollable boxes should be assumed to be scrolled to their
      * origin.
     \*---------------------------------------------------------------------------*/

     // see FIXME 1
     // Calculate the static distance if needed.
     computeInlineStaticDistance(logicalLeftLength, logicalRightLength, this, containerBlock, containerLogicalWidth, fragment);

     // Calculate constraint equation values for 'width' case.
     computePositionedLogicalWidthUsing(MainOrPreferredSize, style().logicalWidth(), containerBlock, containerDirection,
                                        containerLogicalWidth, bordersPlusPadding,
                                        logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
                                        computedValues);

     // Calculate constraint equation values for 'max-width' case.
     if (!style().logicalMaxWidth().isUndefined()) {
         LogicalExtentComputedValues maxValues;

         computePositionedLogicalWidthUsing(MaxSize, style().logicalMaxWidth(), containerBlock, containerDirection,
                                            containerLogicalWidth, bordersPlusPadding,
                                            logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
                                            maxValues);

         if (computedValues.m_extent > maxValues.m_extent) {
             computedValues.m_extent = maxValues.m_extent;
             computedValues.m_position = maxValues.m_position;
             computedValues.m_margins.m_start = maxValues.m_margins.m_start;
             computedValues.m_margins.m_end = maxValues.m_margins.m_end;
         }
     }

     // Calculate constraint equation values for 'min-width' case.
     if (!style().logicalMinWidth().isZero() || style().logicalMinWidth().isIntrinsic()) {
         LogicalExtentComputedValues minValues;

         computePositionedLogicalWidthUsing(MinSize, style().logicalMinWidth(), containerBlock, containerDirection,
                                            containerLogicalWidth, bordersPlusPadding,
                                            logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
                                            minValues);

         if (computedValues.m_extent < minValues.m_extent) {
             computedValues.m_extent = minValues.m_extent;
             computedValues.m_position = minValues.m_position;
             computedValues.m_margins.m_start = minValues.m_margins.m_start;
             computedValues.m_margins.m_end = minValues.m_margins.m_end;
         }
     }

     computedValues.m_extent += bordersPlusPadding;
     if (is<RenderBox>(containerBlock)) {
         auto& containingBox = downcast<RenderBox>(containerBlock);
         if (containingBox.shouldPlaceBlockDirectionScrollbarOnLeft())
             computedValues.m_position += containingBox.verticalScrollbarWidth();
     }

     // Adjust logicalLeft if we need to for the flipped version of our writing mode in fragments.
     // FIXME: Add support for other types of objects as containerBlock, not only RenderBlock.
     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (fragmentedFlow && !fragment && isWritingModeRoot() && isHorizontalWritingMode() == containerBlock.isHorizontalWritingMode() && is<RenderBlock>(containerBlock)) {
         ASSERT(containerBlock.canHaveBoxInfoInFragment());
         LayoutUnit logicalLeftPos = computedValues.m_position;
         const RenderBlock& renderBlock = downcast<RenderBlock>(containerBlock);
         LayoutUnit cbPageOffset = renderBlock.offsetFromLogicalTopOfFirstPage();
         RenderFragmentContainer* cbFragment = renderBlock.fragmentAtBlockOffset(cbPageOffset);
         if (cbFragment) {
             RenderBoxFragmentInfo* boxInfo = renderBlock.renderBoxFragmentInfo(cbFragment);
             if (boxInfo) {
                 logicalLeftPos += boxInfo->logicalLeft();
                 computedValues.m_position = logicalLeftPos;
             }
         }
     }
 }

 static void computeLogicalLeftPositionedOffset(LayoutUnit& logicalLeftPos, const RenderBox* child, LayoutUnit logicalWidthValue, const RenderBoxModelObject& containerBlock, LayoutUnit containerLogicalWidth)
 {
     // Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space. If the containing block is flipped
     // along this axis, then we need to flip the coordinate.  This can only happen if the containing block is both a flipped mode and perpendicular to us.
     if (containerBlock.isHorizontalWritingMode() != child->isHorizontalWritingMode() && containerBlock.style().isFlippedBlocksWritingMode()) {
         logicalLeftPos = containerLogicalWidth - logicalWidthValue - logicalLeftPos;
         logicalLeftPos += (child->isHorizontalWritingMode() ? containerBlock.borderRight() : containerBlock.borderBottom());
     } else
         logicalLeftPos += (child->isHorizontalWritingMode() ? containerBlock.borderLeft() : containerBlock.borderTop());
 }

 void RenderBox::computePositionedLogicalWidthUsing(SizeType widthType, Length logicalWidth, const RenderBoxModelObject& containerBlock, TextDirection containerDirection,
                                                    LayoutUnit containerLogicalWidth, LayoutUnit bordersPlusPadding,
                                                    Length logicalLeft, Length logicalRight, Length marginLogicalLeft, Length marginLogicalRight,
                                                    LogicalExtentComputedValues& computedValues) const
 {
     ASSERT(widthType == MinSize || widthType == MainOrPreferredSize || !logicalWidth.isAuto());
     if (widthType == MinSize && logicalWidth.isAuto())
         logicalWidth = Length(0, Fixed);
     else if (logicalWidth.isIntrinsic())
         logicalWidth = Length(computeIntrinsicLogicalWidthUsing(logicalWidth, containerLogicalWidth, bordersPlusPadding) - bordersPlusPadding, Fixed);

     // 'left' and 'right' cannot both be 'auto' because one would of been
     // converted to the static position already
     ASSERT(!(logicalLeft.isAuto() && logicalRight.isAuto()));

     LayoutUnit logicalLeftValue;

     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, nullptr, false);

     bool logicalWidthIsAuto = logicalWidth.isIntrinsicOrAuto();
     bool logicalLeftIsAuto = logicalLeft.isAuto();
     bool logicalRightIsAuto = logicalRight.isAuto();
     LayoutUnit& marginLogicalLeftValue = style().isLeftToRightDirection() ? computedValues.m_margins.m_start : computedValues.m_margins.m_end;
     LayoutUnit& marginLogicalRightValue = style().isLeftToRightDirection() ? computedValues.m_margins.m_end : computedValues.m_margins.m_start;

     if (!logicalLeftIsAuto && !logicalWidthIsAuto && !logicalRightIsAuto) {
         /*-----------------------------------------------------------------------*\
          * If none of the three is 'auto': If both 'margin-left' and 'margin-
          * right' are 'auto', solve the equation under the extra constraint that
          * the two margins get equal values, unless this would make them negative,
          * in which case when direction of the containing block is 'ltr' ('rtl'),
          * set 'margin-left' ('margin-right') to zero and solve for 'margin-right'
          * ('margin-left'). If one of 'margin-left' or 'margin-right' is 'auto',
          * solve the equation for that value. If the values are over-constrained,
          * ignore the value for 'left' (in case the 'direction' property of the
          * containing block is 'rtl') or 'right' (in case 'direction' is 'ltr')
          * and solve for that value.
         \*-----------------------------------------------------------------------*/
         // NOTE:  It is not necessary to solve for 'right' in the over constrained
         // case because the value is not used for any further calculations.

         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
         computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));

         const LayoutUnit availableSpace = containerLogicalWidth - (logicalLeftValue + computedValues.m_extent + valueForLength(logicalRight, containerLogicalWidth) + bordersPlusPadding);

         // Margins are now the only unknown
         if (marginLogicalLeft.isAuto() && marginLogicalRight.isAuto()) {
             // Both margins auto, solve for equality
             if (availableSpace >= 0) {
                 marginLogicalLeftValue = availableSpace / 2; // split the difference
                 marginLogicalRightValue = availableSpace - marginLogicalLeftValue; // account for odd valued differences
             } else {
                 // Use the containing block's direction rather than the parent block's
                 // per CSS 2.1 reference test abspos-non-replaced-width-margin-000.
                 if (containerDirection == TextDirection::LTR) {
                     marginLogicalLeftValue = 0;
                     marginLogicalRightValue = availableSpace; // will be negative
                 } else {
                     marginLogicalLeftValue = availableSpace; // will be negative
                     marginLogicalRightValue = 0;
                 }
             }
         } else if (marginLogicalLeft.isAuto()) {
             // Solve for left margin
             marginLogicalRightValue = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
             marginLogicalLeftValue = availableSpace - marginLogicalRightValue;
         } else if (marginLogicalRight.isAuto()) {
             // Solve for right margin
             marginLogicalLeftValue = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
             marginLogicalRightValue = availableSpace - marginLogicalLeftValue;
         } else {
             // Over-constrained, solve for left if direction is RTL
             marginLogicalLeftValue = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
             marginLogicalRightValue = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);

             // Use the containing block's direction rather than the parent block's
             // per CSS 2.1 reference test abspos-non-replaced-width-margin-000.
             if (containerDirection == TextDirection::RTL)
                 logicalLeftValue = (availableSpace + logicalLeftValue) - marginLogicalLeftValue - marginLogicalRightValue;
         }
     } else {
         /*--------------------------------------------------------------------*\
          * Otherwise, set 'auto' values for 'margin-left' and 'margin-right'
          * to 0, and pick the one of the following six rules that applies.
          *
          * 1. 'left' and 'width' are 'auto' and 'right' is not 'auto', then the
          *    width is shrink-to-fit. Then solve for 'left'
          *
          *              OMIT RULE 2 AS IT SHOULD NEVER BE HIT
          * ------------------------------------------------------------------
          * 2. 'left' and 'right' are 'auto' and 'width' is not 'auto', then if
          *    the 'direction' property of the containing block is 'ltr' set
          *    'left' to the static position, otherwise set 'right' to the
          *    static position. Then solve for 'left' (if 'direction is 'rtl')
          *    or 'right' (if 'direction' is 'ltr').
          * ------------------------------------------------------------------
          *
          * 3. 'width' and 'right' are 'auto' and 'left' is not 'auto', then the
          *    width is shrink-to-fit . Then solve for 'right'
          * 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve
          *    for 'left'
          * 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve
          *    for 'width'
          * 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve
          *    for 'right'
          *
          * Calculation of the shrink-to-fit width is similar to calculating the
          * width of a table cell using the automatic table layout algorithm.
          * Roughly: calculate the preferred width by formatting the content
          * without breaking lines other than where explicit line breaks occur,
          * and also calculate the preferred minimum width, e.g., by trying all
          * possible line breaks. CSS 2.1 does not define the exact algorithm.
          * Thirdly, calculate the available width: this is found by solving
          * for 'width' after setting 'left' (in case 1) or 'right' (in case 3)
          * to 0.
          *
          * Then the shrink-to-fit width is:
          * min(max(preferred minimum width, available width), preferred width).
         \*--------------------------------------------------------------------*/
         // NOTE: For rules 3 and 6 it is not necessary to solve for 'right'
         // because the value is not used for any further calculations.

         // Calculate margins, 'auto' margins are ignored.
         marginLogicalLeftValue = minimumValueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
         marginLogicalRightValue = minimumValueForLength(marginLogicalRight, containerRelativeLogicalWidth);

         const LayoutUnit availableSpace = containerLogicalWidth - (marginLogicalLeftValue + marginLogicalRightValue + bordersPlusPadding);

         // FIXME: Is there a faster way to find the correct case?
         // Use rule/case that applies.
         if (logicalLeftIsAuto && logicalWidthIsAuto && !logicalRightIsAuto) {
             // RULE 1: (use shrink-to-fit for width, and solve of left)
             LayoutUnit logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

             // FIXME: would it be better to have shrink-to-fit in one step?
             LayoutUnit preferredWidth = maxPreferredLogicalWidth() - bordersPlusPadding;
             LayoutUnit preferredMinWidth = minPreferredLogicalWidth() - bordersPlusPadding;
             LayoutUnit availableWidth = availableSpace - logicalRightValue;
             computedValues.m_extent = std::min(std::max(preferredMinWidth, availableWidth), preferredWidth);
             logicalLeftValue = availableSpace - (computedValues.m_extent + logicalRightValue);
         } else if (!logicalLeftIsAuto && logicalWidthIsAuto && logicalRightIsAuto) {
             // RULE 3: (use shrink-to-fit for width, and no need solve of right)
             logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);

             // FIXME: would it be better to have shrink-to-fit in one step?
             LayoutUnit preferredWidth = maxPreferredLogicalWidth() - bordersPlusPadding;
             LayoutUnit preferredMinWidth = minPreferredLogicalWidth() - bordersPlusPadding;
             LayoutUnit availableWidth = availableSpace - logicalLeftValue;
             computedValues.m_extent = std::min(std::max(preferredMinWidth, availableWidth), preferredWidth);
         } else if (logicalLeftIsAuto && !logicalWidthIsAuto && !logicalRightIsAuto) {
             // RULE 4: (solve for left)
             computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
             logicalLeftValue = availableSpace - (computedValues.m_extent + valueForLength(logicalRight, containerLogicalWidth));
         } else if (!logicalLeftIsAuto && logicalWidthIsAuto && !logicalRightIsAuto) {
             // RULE 5: (solve for width)
             logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
             computedValues.m_extent = availableSpace - (logicalLeftValue + valueForLength(logicalRight, containerLogicalWidth));
         } else if (!logicalLeftIsAuto && !logicalWidthIsAuto && logicalRightIsAuto) {
             // RULE 6: (no need solve for right)
             logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
             computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
         }
     }

     // Use computed values to calculate the horizontal position.

     // FIXME: This hack is needed to calculate the  logical left position for a 'rtl' relatively
     // positioned, inline because right now, it is using the logical left position
     // of the first line box when really it should use the last line box.  When
     // this is fixed elsewhere, this block should be removed.
     if (is<RenderInline>(containerBlock) && !containerBlock.style().isLeftToRightDirection()) {
         const auto& flow = downcast<RenderInline>(containerBlock);
         InlineFlowBox* firstLine = flow.firstLineBox();
         InlineFlowBox* lastLine = flow.lastLineBox();
         if (firstLine && lastLine && firstLine != lastLine) {
             computedValues.m_position = logicalLeftValue + marginLogicalLeftValue + lastLine->borderLogicalLeft() + (lastLine->logicalLeft() - firstLine->logicalLeft());
             return;
         }
     }

     computedValues.m_position = logicalLeftValue + marginLogicalLeftValue;
     computeLogicalLeftPositionedOffset(computedValues.m_position, this, computedValues.m_extent, containerBlock, containerLogicalWidth);
 }

 static void computeBlockStaticDistance(Length& logicalTop, Length& logicalBottom, const RenderBox* child, const RenderBoxModelObject& containerBlock)
 {
     if (!logicalTop.isAuto() || !logicalBottom.isAuto())
         return;

     // FIXME: The static distance computation has not been patched for mixed writing modes.
     LayoutUnit staticLogicalTop = child->layer()->staticBlockPosition() - containerBlock.borderBefore();
     for (RenderElement* container = child->parent(); container && container != &containerBlock; container = container->container()) {
         if (!is<RenderBox>(*container))
             continue;
         const auto& renderBox = downcast<RenderBox>(*container);
         if (!is<RenderTableRow>(renderBox))
             staticLogicalTop += renderBox.logicalTop();
         if (renderBox.isInFlowPositioned())
             staticLogicalTop += renderBox.isHorizontalWritingMode() ? renderBox.offsetForInFlowPosition().height() : renderBox.offsetForInFlowPosition().width();
     }
     logicalTop.setValue(Fixed, staticLogicalTop);
 }

 void RenderBox::computePositionedLogicalHeight(LogicalExtentComputedValues& computedValues) const
 {
     if (isReplaced()) {
         computePositionedLogicalHeightReplaced(computedValues);
         return;
     }

     // The following is based off of the W3C Working Draft from April 11, 2006 of
     // CSS 2.1: Section 10.6.4 "Absolutely positioned, non-replaced elements"
     // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-non-replaced-height>
     // (block-style-comments in this function and in computePositionedLogicalHeightUsing()
     // correspond to text from the spec)


     // We don't use containingBlock(), since we may be positioned by an enclosing relpositioned inline.
     const RenderBoxModelObject& containerBlock = downcast<RenderBoxModelObject>(*container());

     const LayoutUnit containerLogicalHeight = containingBlockLogicalHeightForPositioned(containerBlock);

     const RenderStyle& styleToUse = style();
     const LayoutUnit bordersPlusPadding = borderAndPaddingLogicalHeight();
     const Length marginBefore = styleToUse.marginBefore();
     const Length marginAfter = styleToUse.marginAfter();
     Length logicalTopLength = styleToUse.logicalTop();
     Length logicalBottomLength = styleToUse.logicalBottom();

     /*---------------------------------------------------------------------------*\
      * For the purposes of this section and the next, the term "static position"
      * (of an element) refers, roughly, to the position an element would have had
      * in the normal flow. More precisely, the static position for 'top' is the
      * distance from the top edge of the containing block to the top margin edge
      * of a hypothetical box that would have been the first box of the element if
      * its 'position' property had been 'static' and 'float' had been 'none'. The
      * value is negative if the hypothetical box is above the containing block.
      *
      * But rather than actually calculating the dimensions of that hypothetical
      * box, user agents are free to make a guess at its probable position.
      *
      * For the purposes of calculating the static position, the containing block
      * of fixed positioned elements is the initial containing block instead of
      * the viewport.
     \*---------------------------------------------------------------------------*/

     // see FIXME 1
     // Calculate the static distance if needed.
     computeBlockStaticDistance(logicalTopLength, logicalBottomLength, this, containerBlock);

     // Calculate constraint equation values for 'height' case.
     LayoutUnit logicalHeight = computedValues.m_extent;
     computePositionedLogicalHeightUsing(MainOrPreferredSize, styleToUse.logicalHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
                                         logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
                                         computedValues);

     // Avoid doing any work in the common case (where the values of min-height and max-height are their defaults).
     // see FIXME 2

     // Calculate constraint equation values for 'max-height' case.
     if (!styleToUse.logicalMaxHeight().isUndefined()) {
         LogicalExtentComputedValues maxValues;

         computePositionedLogicalHeightUsing(MaxSize, styleToUse.logicalMaxHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
                                             logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
                                             maxValues);

         if (computedValues.m_extent > maxValues.m_extent) {
             computedValues.m_extent = maxValues.m_extent;
             computedValues.m_position = maxValues.m_position;
             computedValues.m_margins.m_before = maxValues.m_margins.m_before;
             computedValues.m_margins.m_after = maxValues.m_margins.m_after;
         }
     }

     // Calculate constraint equation values for 'min-height' case.
     if (!styleToUse.logicalMinHeight().isZero() || styleToUse.logicalMinHeight().isIntrinsic()) {
         LogicalExtentComputedValues minValues;

         computePositionedLogicalHeightUsing(MinSize, styleToUse.logicalMinHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
                                             logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
                                             minValues);

         if (computedValues.m_extent < minValues.m_extent) {
             computedValues.m_extent = minValues.m_extent;
             computedValues.m_position = minValues.m_position;
             computedValues.m_margins.m_before = minValues.m_margins.m_before;
             computedValues.m_margins.m_after = minValues.m_margins.m_after;
         }
     }

     // Set final height value.
     computedValues.m_extent += bordersPlusPadding;

     // Adjust logicalTop if we need to for perpendicular writing modes in fragments.
     // FIXME: Add support for other types of objects as containerBlock, not only RenderBlock.
     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (fragmentedFlow && isHorizontalWritingMode() != containerBlock.isHorizontalWritingMode() && is<RenderBlock>(containerBlock)) {
         ASSERT(containerBlock.canHaveBoxInfoInFragment());
         LayoutUnit logicalTopPos = computedValues.m_position;
         const RenderBlock& renderBox = downcast<RenderBlock>(containerBlock);
         LayoutUnit cbPageOffset = renderBox.offsetFromLogicalTopOfFirstPage() - logicalLeft();
         RenderFragmentContainer* cbFragment = renderBox.fragmentAtBlockOffset(cbPageOffset);
         if (cbFragment) {
             RenderBoxFragmentInfo* boxInfo = renderBox.renderBoxFragmentInfo(cbFragment);
             if (boxInfo) {
                 logicalTopPos += boxInfo->logicalLeft();
                 computedValues.m_position = logicalTopPos;
             }
         }
     }
 }

 static void computeLogicalTopPositionedOffset(LayoutUnit& logicalTopPos, const RenderBox* child, LayoutUnit logicalHeightValue, const RenderBoxModelObject& containerBlock, LayoutUnit containerLogicalHeight)
 {
     // Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space. If the containing block is flipped
     // along this axis, then we need to flip the coordinate.  This can only happen if the containing block is both a flipped mode and perpendicular to us.
     if ((child->style().isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() != containerBlock.isHorizontalWritingMode())
         || (child->style().isFlippedBlocksWritingMode() != containerBlock.style().isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() == containerBlock.isHorizontalWritingMode()))
         logicalTopPos = containerLogicalHeight - logicalHeightValue - logicalTopPos;

     // Our offset is from the logical bottom edge in a flipped environment, e.g., right for vertical-rl and bottom for horizontal-bt.
     if (containerBlock.style().isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() == containerBlock.isHorizontalWritingMode()) {
         if (child->isHorizontalWritingMode())
             logicalTopPos += containerBlock.borderBottom();
         else
             logicalTopPos += containerBlock.borderRight();
     } else {
         if (child->isHorizontalWritingMode())
             logicalTopPos += containerBlock.borderTop();
         else
             logicalTopPos += containerBlock.borderLeft();
     }
 }

 void RenderBox::computePositionedLogicalHeightUsing(SizeType heightType, Length logicalHeightLength, const RenderBoxModelObject& containerBlock,
                                                     LayoutUnit containerLogicalHeight, LayoutUnit bordersPlusPadding, LayoutUnit logicalHeight,
                                                     Length logicalTop, Length logicalBottom, Length marginBefore, Length marginAfter,
                                                     LogicalExtentComputedValues& computedValues) const
 {
     ASSERT(heightType == MinSize || heightType == MainOrPreferredSize || !logicalHeightLength.isAuto());
     if (heightType == MinSize && logicalHeightLength.isAuto())
         logicalHeightLength = Length(0, Fixed);

     // 'top' and 'bottom' cannot both be 'auto' because 'top would of been
     // converted to the static position in computePositionedLogicalHeight()
     ASSERT(!(logicalTop.isAuto() && logicalBottom.isAuto()));

     LayoutUnit logicalHeightValue;
     LayoutUnit contentLogicalHeight = logicalHeight - bordersPlusPadding;

     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, nullptr, false);

     LayoutUnit logicalTopValue;

     bool logicalHeightIsAuto = logicalHeightLength.isAuto();
     bool logicalTopIsAuto = logicalTop.isAuto();
     bool logicalBottomIsAuto = logicalBottom.isAuto();

     // Height is never unsolved for tables.
     LayoutUnit resolvedLogicalHeight;
     if (isTable()) {
         resolvedLogicalHeight = contentLogicalHeight;
         logicalHeightIsAuto = false;
     } else {
         if (logicalHeightLength.isIntrinsic())
             resolvedLogicalHeight = computeIntrinsicLogicalContentHeightUsing(logicalHeightLength, contentLogicalHeight, bordersPlusPadding).value();
         else
             resolvedLogicalHeight = adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeightLength, containerLogicalHeight));
     }

     if (!logicalTopIsAuto && !logicalHeightIsAuto && !logicalBottomIsAuto) {
         /*-----------------------------------------------------------------------*\
          * If none of the three are 'auto': If both 'margin-top' and 'margin-
          * bottom' are 'auto', solve the equation under the extra constraint that
          * the two margins get equal values. If one of 'margin-top' or 'margin-
          * bottom' is 'auto', solve the equation for that value. If the values
          * are over-constrained, ignore the value for 'bottom' and solve for that
          * value.
         \*-----------------------------------------------------------------------*/
         // NOTE:  It is not necessary to solve for 'bottom' in the over constrained
         // case because the value is not used for any further calculations.

         logicalHeightValue = resolvedLogicalHeight;
         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);

         const LayoutUnit availableSpace = containerLogicalHeight - (logicalTopValue + logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight) + bordersPlusPadding);

         // Margins are now the only unknown
         if (marginBefore.isAuto() && marginAfter.isAuto()) {
             // Both margins auto, solve for equality
             // NOTE: This may result in negative values.
             computedValues.m_margins.m_before = availableSpace / 2; // split the difference
             computedValues.m_margins.m_after = availableSpace - computedValues.m_margins.m_before; // account for odd valued differences
         } else if (marginBefore.isAuto()) {
             // Solve for top margin
             computedValues.m_margins.m_after = valueForLength(marginAfter, containerRelativeLogicalWidth);
             computedValues.m_margins.m_before = availableSpace - computedValues.m_margins.m_after;
         } else if (marginAfter.isAuto()) {
             // Solve for bottom margin
             computedValues.m_margins.m_before = valueForLength(marginBefore, containerRelativeLogicalWidth);
             computedValues.m_margins.m_after = availableSpace - computedValues.m_margins.m_before;
         } else {
             // Over-constrained, (no need solve for bottom)
             computedValues.m_margins.m_before = valueForLength(marginBefore, containerRelativeLogicalWidth);
             computedValues.m_margins.m_after = valueForLength(marginAfter, containerRelativeLogicalWidth);
         }
     } else {
         /*--------------------------------------------------------------------*\
          * Otherwise, set 'auto' values for 'margin-top' and 'margin-bottom'
          * to 0, and pick the one of the following six rules that applies.
          *
          * 1. 'top' and 'height' are 'auto' and 'bottom' is not 'auto', then
          *    the height is based on the content, and solve for 'top'.
          *
          *              OMIT RULE 2 AS IT SHOULD NEVER BE HIT
          * ------------------------------------------------------------------
          * 2. 'top' and 'bottom' are 'auto' and 'height' is not 'auto', then
          *    set 'top' to the static position, and solve for 'bottom'.
          * ------------------------------------------------------------------
          *
          * 3. 'height' and 'bottom' are 'auto' and 'top' is not 'auto', then
          *    the height is based on the content, and solve for 'bottom'.
          * 4. 'top' is 'auto', 'height' and 'bottom' are not 'auto', and
          *    solve for 'top'.
          * 5. 'height' is 'auto', 'top' and 'bottom' are not 'auto', and
          *    solve for 'height'.
          * 6. 'bottom' is 'auto', 'top' and 'height' are not 'auto', and
          *    solve for 'bottom'.
         \*--------------------------------------------------------------------*/
         // NOTE: For rules 3 and 6 it is not necessary to solve for 'bottom'
         // because the value is not used for any further calculations.

         // Calculate margins, 'auto' margins are ignored.
         computedValues.m_margins.m_before = minimumValueForLength(marginBefore, containerRelativeLogicalWidth);
         computedValues.m_margins.m_after = minimumValueForLength(marginAfter, containerRelativeLogicalWidth);

         const LayoutUnit availableSpace = containerLogicalHeight - (computedValues.m_margins.m_before + computedValues.m_margins.m_after + bordersPlusPadding);

         // Use rule/case that applies.
         if (logicalTopIsAuto && logicalHeightIsAuto && !logicalBottomIsAuto) {
             // RULE 1: (height is content based, solve of top)
             logicalHeightValue = contentLogicalHeight;
             logicalTopValue = availableSpace - (logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight));
         } else if (!logicalTopIsAuto && logicalHeightIsAuto && logicalBottomIsAuto) {
             // RULE 3: (height is content based, no need solve of bottom)
             logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
             logicalHeightValue = contentLogicalHeight;
         } else if (logicalTopIsAuto && !logicalHeightIsAuto && !logicalBottomIsAuto) {
             // RULE 4: (solve of top)
             logicalHeightValue = resolvedLogicalHeight;
             logicalTopValue = availableSpace - (logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight));
         } else if (!logicalTopIsAuto && logicalHeightIsAuto && !logicalBottomIsAuto) {
             // RULE 5: (solve of height)
             logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
             logicalHeightValue = std::max<LayoutUnit>(0, availableSpace - (logicalTopValue + valueForLength(logicalBottom, containerLogicalHeight)));
         } else if (!logicalTopIsAuto && !logicalHeightIsAuto && logicalBottomIsAuto) {
             // RULE 6: (no need solve of bottom)
             logicalHeightValue = resolvedLogicalHeight;
             logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
         }
     }
     computedValues.m_extent = logicalHeightValue;

     // Use computed values to calculate the vertical position.
     computedValues.m_position = logicalTopValue + computedValues.m_margins.m_before;
     computeLogicalTopPositionedOffset(computedValues.m_position, this, logicalHeightValue, containerBlock, containerLogicalHeight);
 }

 void RenderBox::computePositionedLogicalWidthReplaced(LogicalExtentComputedValues& computedValues) const
 {
     // The following is based off of the W3C Working Draft from April 11, 2006 of
     // CSS 2.1: Section 10.3.8 "Absolutely positioned, replaced elements"
     // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-replaced-width>
     // (block-style-comments in this function correspond to text from the spec and
     // the numbers correspond to numbers in spec)

     // We don't use containingBlock(), since we may be positioned by an enclosing
     // relative positioned inline.
     const RenderBoxModelObject& containerBlock = downcast<RenderBoxModelObject>(*container());

     const LayoutUnit containerLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock);
     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, nullptr, false);

     // To match WinIE, in quirks mode use the parent's 'direction' property
     // instead of the container block's.
     TextDirection containerDirection = containerBlock.style().direction();

     // Variables to solve.
     bool isHorizontal = isHorizontalWritingMode();
     Length logicalLeft = style().logicalLeft();
     Length logicalRight = style().logicalRight();
     Length marginLogicalLeft = isHorizontal ? style().marginLeft() : style().marginTop();
     Length marginLogicalRight = isHorizontal ? style().marginRight() : style().marginBottom();
     LayoutUnit& marginLogicalLeftAlias = style().isLeftToRightDirection() ? computedValues.m_margins.m_start : computedValues.m_margins.m_end;
     LayoutUnit& marginLogicalRightAlias = style().isLeftToRightDirection() ? computedValues.m_margins.m_end : computedValues.m_margins.m_start;

     /*-----------------------------------------------------------------------*\
      * 1. The used value of 'width' is determined as for inline replaced
      *    elements.
     \*-----------------------------------------------------------------------*/
     // NOTE: This value of width is final in that the min/max width calculations
     // are dealt with in computeReplacedWidth().  This means that the steps to produce
     // correct max/min in the non-replaced version, are not necessary.
     computedValues.m_extent = computeReplacedLogicalWidth() + borderAndPaddingLogicalWidth();

     const LayoutUnit availableSpace = containerLogicalWidth - computedValues.m_extent;

     /*-----------------------------------------------------------------------*\
      * 2. If both 'left' and 'right' have the value 'auto', then if 'direction'
      *    of the containing block is 'ltr', set 'left' to the static position;
      *    else if 'direction' is 'rtl', set 'right' to the static position.
     \*-----------------------------------------------------------------------*/
     // see FIXME 1
     computeInlineStaticDistance(logicalLeft, logicalRight, this, containerBlock, containerLogicalWidth, nullptr); // FIXME: Pass the fragment.

     /*-----------------------------------------------------------------------*\
      * 3. If 'left' or 'right' are 'auto', replace any 'auto' on 'margin-left'
      *    or 'margin-right' with '0'.
     \*-----------------------------------------------------------------------*/
     if (logicalLeft.isAuto() || logicalRight.isAuto()) {
         if (marginLogicalLeft.isAuto())
             marginLogicalLeft.setValue(Fixed, 0);
         if (marginLogicalRight.isAuto())
             marginLogicalRight.setValue(Fixed, 0);
     }

     /*-----------------------------------------------------------------------*\
      * 4. If at this point both 'margin-left' and 'margin-right' are still
      *    'auto', solve the equation under the extra constraint that the two
      *    margins must get equal values, unless this would make them negative,
      *    in which case when the direction of the containing block is 'ltr'
      *    ('rtl'), set 'margin-left' ('margin-right') to zero and solve for
      *    'margin-right' ('margin-left').
     \*-----------------------------------------------------------------------*/
     LayoutUnit logicalLeftValue;
     LayoutUnit logicalRightValue;

     if (marginLogicalLeft.isAuto() && marginLogicalRight.isAuto()) {
         // 'left' and 'right' cannot be 'auto' due to step 3
         ASSERT(!(logicalLeft.isAuto() && logicalRight.isAuto()));

         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

         LayoutUnit difference = availableSpace - (logicalLeftValue + logicalRightValue);
         if (difference > 0) {
             marginLogicalLeftAlias = difference / 2; // split the difference
             marginLogicalRightAlias = difference - marginLogicalLeftAlias; // account for odd valued differences
         } else {
             // Use the containing block's direction rather than the parent block's
             // per CSS 2.1 reference test abspos-replaced-width-margin-000.
             if (containerDirection == TextDirection::LTR) {
                 marginLogicalLeftAlias = 0;
                 marginLogicalRightAlias = difference; // will be negative
             } else {
                 marginLogicalLeftAlias = difference; // will be negative
                 marginLogicalRightAlias = 0;
             }
         }

     /*-----------------------------------------------------------------------*\
      * 5. If at this point there is an 'auto' left, solve the equation for
      *    that value.
     \*-----------------------------------------------------------------------*/
     } else if (logicalLeft.isAuto()) {
         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

         // Solve for 'left'
         logicalLeftValue = availableSpace - (logicalRightValue + marginLogicalLeftAlias + marginLogicalRightAlias);
     } else if (logicalRight.isAuto()) {
         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);

         // Solve for 'right'
         logicalRightValue = availableSpace - (logicalLeftValue + marginLogicalLeftAlias + marginLogicalRightAlias);
     } else if (marginLogicalLeft.isAuto()) {
         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

         // Solve for 'margin-left'
         marginLogicalLeftAlias = availableSpace - (logicalLeftValue + logicalRightValue + marginLogicalRightAlias);
     } else if (marginLogicalRight.isAuto()) {
         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);

         // Solve for 'margin-right'
         marginLogicalRightAlias = availableSpace - (logicalLeftValue + logicalRightValue + marginLogicalLeftAlias);
     } else {
         // Nothing is 'auto', just calculate the values.
         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
         // If the containing block is right-to-left, then push the left position as far to the right as possible
         if (containerDirection == TextDirection::RTL) {
             int totalLogicalWidth = computedValues.m_extent + logicalLeftValue + logicalRightValue +  marginLogicalLeftAlias + marginLogicalRightAlias;
             logicalLeftValue = containerLogicalWidth - (totalLogicalWidth - logicalLeftValue);
         }
     }

     /*-----------------------------------------------------------------------*\
      * 6. If at this point the values are over-constrained, ignore the value
      *    for either 'left' (in case the 'direction' property of the
      *    containing block is 'rtl') or 'right' (in case 'direction' is
      *    'ltr') and solve for that value.
     \*-----------------------------------------------------------------------*/
     // NOTE: Constraints imposed by the width of the containing block and its content have already been accounted for above.

     // FIXME: Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space, so that
     // can make the result here rather complicated to compute.

     // Use computed values to calculate the horizontal position.

     // FIXME: This hack is needed to calculate the logical left position for a 'rtl' relatively
     // positioned, inline containing block because right now, it is using the logical left position
     // of the first line box when really it should use the last line box.  When
     // this is fixed elsewhere, this block should be removed.
     if (is<RenderInline>(containerBlock) && !containerBlock.style().isLeftToRightDirection()) {
         const auto& flow = downcast<RenderInline>(containerBlock);
         InlineFlowBox* firstLine = flow.firstLineBox();
         InlineFlowBox* lastLine = flow.lastLineBox();
         if (firstLine && lastLine && firstLine != lastLine) {
             computedValues.m_position = logicalLeftValue + marginLogicalLeftAlias + lastLine->borderLogicalLeft() + (lastLine->logicalLeft() - firstLine->logicalLeft());
             return;
         }
     }

     LayoutUnit logicalLeftPos = logicalLeftValue + marginLogicalLeftAlias;
     computeLogicalLeftPositionedOffset(logicalLeftPos, this, computedValues.m_extent, containerBlock, containerLogicalWidth);
     computedValues.m_position = logicalLeftPos;
 }

 void RenderBox::computePositionedLogicalHeightReplaced(LogicalExtentComputedValues& computedValues) const
 {
     // The following is based off of the W3C Working Draft from April 11, 2006 of
     // CSS 2.1: Section 10.6.5 "Absolutely positioned, replaced elements"
     // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-replaced-height>
     // (block-style-comments in this function correspond to text from the spec and
     // the numbers correspond to numbers in spec)

     // We don't use containingBlock(), since we may be positioned by an enclosing relpositioned inline.
     const RenderBoxModelObject& containerBlock = downcast<RenderBoxModelObject>(*container());

     const LayoutUnit containerLogicalHeight = containingBlockLogicalHeightForPositioned(containerBlock);
     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, nullptr, false);

     // Variables to solve.
     Length marginBefore = style().marginBefore();
     Length marginAfter = style().marginAfter();
     LayoutUnit& marginBeforeAlias = computedValues.m_margins.m_before;
     LayoutUnit& marginAfterAlias = computedValues.m_margins.m_after;

     Length logicalTop = style().logicalTop();
     Length logicalBottom = style().logicalBottom();

     /*-----------------------------------------------------------------------*\
      * 1. The used value of 'height' is determined as for inline replaced
      *    elements.
     \*-----------------------------------------------------------------------*/
     // NOTE: This value of height is final in that the min/max height calculations
     // are dealt with in computeReplacedHeight().  This means that the steps to produce
     // correct max/min in the non-replaced version, are not necessary.
     computedValues.m_extent = computeReplacedLogicalHeight() + borderAndPaddingLogicalHeight();
     const LayoutUnit availableSpace = containerLogicalHeight - computedValues.m_extent;

     /*-----------------------------------------------------------------------*\
      * 2. If both 'top' and 'bottom' have the value 'auto', replace 'top'
      *    with the element's static position.
     \*-----------------------------------------------------------------------*/
     // see FIXME 1
     computeBlockStaticDistance(logicalTop, logicalBottom, this, containerBlock);

     /*-----------------------------------------------------------------------*\
      * 3. If 'bottom' is 'auto', replace any 'auto' on 'margin-top' or
      *    'margin-bottom' with '0'.
     \*-----------------------------------------------------------------------*/
     // FIXME: The spec. says that this step should only be taken when bottom is
     // auto, but if only top is auto, this makes step 4 impossible.
     if (logicalTop.isAuto() || logicalBottom.isAuto()) {
         if (marginBefore.isAuto())
             marginBefore.setValue(Fixed, 0);
         if (marginAfter.isAuto())
             marginAfter.setValue(Fixed, 0);
     }

     /*-----------------------------------------------------------------------*\
      * 4. If at this point both 'margin-top' and 'margin-bottom' are still
      *    'auto', solve the equation under the extra constraint that the two
      *    margins must get equal values.
     \*-----------------------------------------------------------------------*/
     LayoutUnit logicalTopValue;
     LayoutUnit logicalBottomValue;

     if (marginBefore.isAuto() && marginAfter.isAuto()) {
         // 'top' and 'bottom' cannot be 'auto' due to step 2 and 3 combined.
         ASSERT(!(logicalTop.isAuto() || logicalBottom.isAuto()));

         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

         LayoutUnit difference = availableSpace - (logicalTopValue + logicalBottomValue);
         // NOTE: This may result in negative values.
         marginBeforeAlias =  difference / 2; // split the difference
         marginAfterAlias = difference - marginBeforeAlias; // account for odd valued differences

     /*-----------------------------------------------------------------------*\
      * 5. If at this point there is only one 'auto' left, solve the equation
      *    for that value.
     \*-----------------------------------------------------------------------*/
     } else if (logicalTop.isAuto()) {
         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

         // Solve for 'top'
         logicalTopValue = availableSpace - (logicalBottomValue + marginBeforeAlias + marginAfterAlias);
     } else if (logicalBottom.isAuto()) {
         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);

         // Solve for 'bottom'
         // NOTE: It is not necessary to solve for 'bottom' because we don't ever
         // use the value.
     } else if (marginBefore.isAuto()) {
         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

         // Solve for 'margin-top'
         marginBeforeAlias = availableSpace - (logicalTopValue + logicalBottomValue + marginAfterAlias);
     } else if (marginAfter.isAuto()) {
         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);

         // Solve for 'margin-bottom'
         marginAfterAlias = availableSpace - (logicalTopValue + logicalBottomValue + marginBeforeAlias);
     } else {
         // Nothing is 'auto', just calculate the values.
         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
         // NOTE: It is not necessary to solve for 'bottom' because we don't ever
         // use the value.
      }

     /*-----------------------------------------------------------------------*\
      * 6. If at this point the values are over-constrained, ignore the value
      *    for 'bottom' and solve for that value.
     \*-----------------------------------------------------------------------*/
     // NOTE: It is not necessary to do this step because we don't end up using
     // the value of 'bottom' regardless of whether the values are over-constrained
     // or not.

     // Use computed values to calculate the vertical position.
     LayoutUnit logicalTopPos = logicalTopValue + marginBeforeAlias;
     computeLogicalTopPositionedOffset(logicalTopPos, this, computedValues.m_extent, containerBlock, containerLogicalHeight);
     computedValues.m_position = logicalTopPos;
 }

 LayoutRect RenderBox::localCaretRect(InlineBox* box, unsigned caretOffset, LayoutUnit* extraWidthToEndOfLine)
 {
     // VisiblePositions at offsets inside containers either a) refer to the positions before/after
     // those containers (tables and select elements) or b) refer to the position inside an empty block.
     // They never refer to children.
     // FIXME: Paint the carets inside empty blocks differently than the carets before/after elements.

     LayoutRect rect(location(), LayoutSize(caretWidth, height()));
     bool ltr = box ? box->isLeftToRightDirection() : style().isLeftToRightDirection();

     if ((!caretOffset) ^ ltr)
         rect.move(LayoutSize(width() - caretWidth, 0_lu));

     if (box) {
         const RootInlineBox& rootBox = box->root();
         LayoutUnit top = rootBox.lineTop();
         rect.setY(top);
         rect.setHeight(rootBox.lineBottom() - top);
     }

     // If height of box is smaller than font height, use the latter one,
     // otherwise the caret might become invisible.
     //
     // Also, if the box is not a replaced element, always use the font height.
     // This prevents the "big caret" bug described in:
     // <rdar://problem/3777804> Deleting all content in a document can result in giant tall-as-window insertion point
     //
     // FIXME: ignoring :first-line, missing good reason to take care of
     LayoutUnit fontHeight = style().fontMetrics().height();
     if (fontHeight > rect.height() || (!isReplaced() && !isTable()))
         rect.setHeight(fontHeight);

     if (extraWidthToEndOfLine)
         *extraWidthToEndOfLine = x() + width() - rect.maxX();

     // Move to local coords
     rect.moveBy(-location());

     // FIXME: Border/padding should be added for all elements but this workaround
     // is needed because we use offsets inside an "atomic" element to represent
     // positions before and after the element in deprecated editing offsets.
     if (element() && !(editingIgnoresContent(*element()) || isRenderedTable(element()))) {
         rect.setX(rect.x() + borderLeft() + paddingLeft());
         rect.setY(rect.y() + paddingTop() + borderTop());
     }

     if (!isHorizontalWritingMode())
         return rect.transposedRect();

     return rect;
 }

 VisiblePosition RenderBox::positionForPoint(const LayoutPoint& point, const RenderFragmentContainer* fragment)
 {
     // no children...return this render object's element, if there is one, and offset 0
     if (!firstChild())
         return createVisiblePosition(nonPseudoElement() ? firstPositionInOrBeforeNode(nonPseudoElement()) : Position());

     if (isTable() && nonPseudoElement()) {
         LayoutUnit right = contentWidth() + horizontalBorderAndPaddingExtent();
         LayoutUnit bottom = contentHeight() + verticalBorderAndPaddingExtent();

         if (point.x() < 0 || point.x() > right || point.y() < 0 || point.y() > bottom) {
             if (point.x() <= right / 2)
                 return createVisiblePosition(firstPositionInOrBeforeNode(nonPseudoElement()));
             return createVisiblePosition(lastPositionInOrAfterNode(nonPseudoElement()));
         }
     }

     // Pass off to the closest child.
     LayoutUnit minDist = LayoutUnit::max();
     RenderBox* closestRenderer = nullptr;
     LayoutPoint adjustedPoint = point;
     if (isTableRow())
         adjustedPoint.moveBy(location());

     for (auto& renderer : childrenOfType<RenderBox>(*this)) {
         if (is<RenderFragmentedFlow>(*this)) {
             ASSERT(fragment);
             if (!downcast<RenderFragmentedFlow>(*this).objectShouldFragmentInFlowFragment(&renderer, fragment))
                 continue;
         }

         if ((!renderer.firstChild() && !renderer.isInline() && !is<RenderBlockFlow>(renderer))
             || renderer.style().visibility() != Visibility::Visible)
             continue;

         LayoutUnit top = renderer.borderTop() + renderer.paddingTop() + (is<RenderTableRow>(*this) ? 0_lu : renderer.y());
         LayoutUnit bottom = top + renderer.contentHeight();
         LayoutUnit left = renderer.borderLeft() + renderer.paddingLeft() + (is<RenderTableRow>(*this) ? 0_lu : renderer.x());
         LayoutUnit right = left + renderer.contentWidth();

         if (point.x() <= right && point.x() >= left && point.y() <= top && point.y() >= bottom) {
             if (is<RenderTableRow>(renderer))
                 return renderer.positionForPoint(point + adjustedPoint - renderer.locationOffset(), fragment);
             return renderer.positionForPoint(point - renderer.locationOffset(), fragment);
         }

         // Find the distance from (x, y) to the box.  Split the space around the box into 8 pieces
         // and use a different compare depending on which piece (x, y) is in.
         LayoutPoint cmp;
         if (point.x() > right) {
             if (point.y() < top)
                 cmp = LayoutPoint(right, top);
             else if (point.y() > bottom)
                 cmp = LayoutPoint(right, bottom);
             else
                 cmp = LayoutPoint(right, point.y());
         } else if (point.x() < left) {
             if (point.y() < top)
                 cmp = LayoutPoint(left, top);
             else if (point.y() > bottom)
                 cmp = LayoutPoint(left, bottom);
             else
                 cmp = LayoutPoint(left, point.y());
         } else {
             if (point.y() < top)
                 cmp = LayoutPoint(point.x(), top);
             else
                 cmp = LayoutPoint(point.x(), bottom);
         }

         LayoutSize difference = cmp - point;

         LayoutUnit dist = difference.width() * difference.width() + difference.height() * difference.height();
         if (dist < minDist) {
             closestRenderer = &renderer;
             minDist = dist;
         }
     }

     if (closestRenderer)
         return closestRenderer->positionForPoint(adjustedPoint - closestRenderer->locationOffset(), fragment);

     return createVisiblePosition(firstPositionInOrBeforeNode(nonPseudoElement()));
 }

 bool RenderBox::shrinkToAvoidFloats() const
 {
     // Floating objects don't shrink.  Objects that don't avoid floats don't shrink.  Marquees don't shrink.
     if ((isInline() && !isHTMLMarquee()) || !avoidsFloats() || isFloating())
         return false;

     // Only auto width objects can possibly shrink to avoid floats.
     return style().width().isAuto();
 }

 bool RenderBox::createsNewFormattingContext() const
 {
     return isInlineBlockOrInlineTable() || isFloatingOrOutOfFlowPositioned() || hasOverflowClip() || isFlexItemIncludingDeprecated()
         || isTableCell() || isTableCaption() || isFieldset() || isWritingModeRoot() || isDocumentElementRenderer() || isRenderFragmentedFlow() || isRenderFragmentContainer()
         || isGridItem() || style().specifiesColumns() || style().columnSpan() == ColumnSpan::All || style().display() == DisplayType::FlowRoot;
 }

 bool RenderBox::avoidsFloats() const
 {
     return isReplaced() || isHR() || isLegend() || isFieldset() || createsNewFormattingContext();
 }

 void RenderBox::addVisualEffectOverflow()
 {
     if (!style().boxShadow() && !style().hasBorderImageOutsets() && !outlineStyleForRepaint().hasOutlineInVisualOverflow())
         return;

     addVisualOverflow(applyVisualEffectOverflow(borderBoxRect()));

     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (fragmentedFlow)
         fragmentedFlow->addFragmentsVisualEffectOverflow(this);
 }

 LayoutRect RenderBox::applyVisualEffectOverflow(const LayoutRect& borderBox) const
 {
     bool isFlipped = style().isFlippedBlocksWritingMode();
     bool isHorizontal = isHorizontalWritingMode();

     LayoutUnit overflowMinX = borderBox.x();
     LayoutUnit overflowMaxX = borderBox.maxX();
     LayoutUnit overflowMinY = borderBox.y();
     LayoutUnit overflowMaxY = borderBox.maxY();

     // Compute box-shadow overflow first.
     if (style().boxShadow()) {
         LayoutUnit shadowLeft;
         LayoutUnit shadowRight;
         LayoutUnit shadowTop;
         LayoutUnit shadowBottom;
         style().getBoxShadowExtent(shadowTop, shadowRight, shadowBottom, shadowLeft);

         // In flipped blocks writing modes such as vertical-rl, the physical right shadow value is actually at the lower x-coordinate.
         overflowMinX = borderBox.x() + ((!isFlipped || isHorizontal) ? shadowLeft : -shadowRight);
         overflowMaxX = borderBox.maxX() + ((!isFlipped || isHorizontal) ? shadowRight : -shadowLeft);
         overflowMinY = borderBox.y() + ((!isFlipped || !isHorizontal) ? shadowTop : -shadowBottom);
         overflowMaxY = borderBox.maxY() + ((!isFlipped || !isHorizontal) ? shadowBottom : -shadowTop);
     }

     // Now compute border-image-outset overflow.
     if (style().hasBorderImageOutsets()) {
         LayoutBoxExtent borderOutsets = style().borderImageOutsets();

         // In flipped blocks writing modes, the physical sides are inverted. For example in vertical-rl, the right
         // border is at the lower x coordinate value.
         overflowMinX = std::min(overflowMinX, borderBox.x() - ((!isFlipped || isHorizontal) ? borderOutsets.left() : borderOutsets.right()));
         overflowMaxX = std::max(overflowMaxX, borderBox.maxX() + ((!isFlipped || isHorizontal) ? borderOutsets.right() : borderOutsets.left()));
         overflowMinY = std::min(overflowMinY, borderBox.y() - ((!isFlipped || !isHorizontal) ? borderOutsets.top() : borderOutsets.bottom()));
         overflowMaxY = std::max(overflowMaxY, borderBox.maxY() + ((!isFlipped || !isHorizontal) ? borderOutsets.bottom() : borderOutsets.top()));
     }

     if (outlineStyleForRepaint().hasOutlineInVisualOverflow()) {
         LayoutUnit outlineSize { outlineStyleForRepaint().outlineSize() };
         overflowMinX = std::min(overflowMinX, borderBox.x() - outlineSize);
         overflowMaxX = std::max(overflowMaxX, borderBox.maxX() + outlineSize);
         overflowMinY = std::min(overflowMinY, borderBox.y() - outlineSize);
         overflowMaxY = std::max(overflowMaxY, borderBox.maxY() + outlineSize);
     }
     // Add in the final overflow with shadows and outsets combined.
     return LayoutRect(overflowMinX, overflowMinY, overflowMaxX - overflowMinX, overflowMaxY - overflowMinY);
 }

 void RenderBox::addOverflowFromChild(const RenderBox* child, const LayoutSize& delta)
 {
     // Never allow flow threads to propagate overflow up to a parent.
     if (child->isRenderFragmentedFlow())
         return;

     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (fragmentedFlow)
         fragmentedFlow->addFragmentsOverflowFromChild(this, child, delta);

     // Only propagate layout overflow from the child if the child isn't clipping its overflow.  If it is, then
     // its overflow is internal to it, and we don't care about it.  layoutOverflowRectForPropagation takes care of this
     // and just propagates the border box rect instead.
     LayoutRect childLayoutOverflowRect = child->layoutOverflowRectForPropagation(&style());
     childLayoutOverflowRect.move(delta);
     addLayoutOverflow(childLayoutOverflowRect);

     // Add in visual overflow from the child.  Even if the child clips its overflow, it may still
     // have visual overflow of its own set from box shadows or reflections.  It is unnecessary to propagate this
     // overflow if we are clipping our own overflow.
     if (child->hasSelfPaintingLayer() || hasOverflowClip())
         return;
     LayoutRect childVisualOverflowRect = child->visualOverflowRectForPropagation(&style());
     childVisualOverflowRect.move(delta);
     addVisualOverflow(childVisualOverflowRect);
 }

 void RenderBox::addLayoutOverflow(const LayoutRect& rect)
 {
     LayoutRect clientBox = flippedClientBoxRect();
     if (clientBox.contains(rect) || rect.isEmpty())
         return;

     // For overflow clip objects, we don't want to propagate overflow into unreachable areas.
     LayoutRect overflowRect(rect);
     if (hasOverflowClip() || isRenderView()) {
         // Overflow is in the block's coordinate space and thus is flipped for horizontal-bt and vertical-rl
         // writing modes.  At this stage that is actually a simplification, since we can treat horizontal-tb/bt as the same
         // and vertical-lr/rl as the same.
         bool hasTopOverflow = isTopLayoutOverflowAllowed();
         bool hasLeftOverflow = isLeftLayoutOverflowAllowed();

         if (!hasTopOverflow)
             overflowRect.shiftYEdgeTo(std::max(overflowRect.y(), clientBox.y()));
         else
             overflowRect.shiftMaxYEdgeTo(std::min(overflowRect.maxY(), clientBox.maxY()));
         if (!hasLeftOverflow)
             overflowRect.shiftXEdgeTo(std::max(overflowRect.x(), clientBox.x()));
         else
             overflowRect.shiftMaxXEdgeTo(std::min(overflowRect.maxX(), clientBox.maxX()));

         // Now re-test with the adjusted rectangle and see if it has become unreachable or fully
         // contained.
         if (clientBox.contains(overflowRect) || overflowRect.isEmpty())
             return;
     }

     if (!m_overflow)
         m_overflow = adoptRef(new RenderOverflow(clientBox, borderBoxRect()));

     m_overflow->addLayoutOverflow(overflowRect);
 }

 void RenderBox::addVisualOverflow(const LayoutRect& rect)
 {
     LayoutRect borderBox = borderBoxRect();
     if (borderBox.contains(rect) || rect.isEmpty())
         return;

     if (!m_overflow)
         m_overflow = adoptRef(new RenderOverflow(flippedClientBoxRect(), borderBox));

     m_overflow->addVisualOverflow(rect);
 }

 void RenderBox::clearOverflow()
 {
     m_overflow = nullptr;
     RenderFragmentedFlow* fragmentedFlow = enclosingFragmentedFlow();
     if (fragmentedFlow)
         fragmentedFlow->clearFragmentsOverflow(this);
 }

 bool RenderBox::percentageLogicalHeightIsResolvable() const
 {
     // Do this to avoid duplicating all the logic that already exists when computing
     // an actual percentage height.
     Length fakeLength(100, Percent);
     return computePercentageLogicalHeight(fakeLength) != WTF::nullopt;
 }

 bool RenderBox::hasUnsplittableScrollingOverflow() const
 {
     // We will paginate as long as we don't scroll overflow in the pagination direction.
     bool isHorizontal = isHorizontalWritingMode();
     if ((isHorizontal && !scrollsOverflowY()) || (!isHorizontal && !scrollsOverflowX()))
         return false;

     // We do have overflow. We'll still be willing to paginate as long as the block
     // has auto logical height, auto or undefined max-logical-height and a zero or auto min-logical-height.
     // Note this is just a heuristic, and it's still possible to have overflow under these
     // conditions, but it should work out to be good enough for common cases. Paginating overflow
     // with scrollbars present is not the end of the world and is what we used to do in the old model anyway.
     return !style().logicalHeight().isIntrinsicOrAuto()
         || (!style().logicalMaxHeight().isIntrinsicOrAuto() && !style().logicalMaxHeight().isUndefined() && (!style().logicalMaxHeight().isPercentOrCalculated() || percentageLogicalHeightIsResolvable()))
         || (!style().logicalMinHeight().isIntrinsicOrAuto() && style().logicalMinHeight().isPositive() && (!style().logicalMinHeight().isPercentOrCalculated() || percentageLogicalHeightIsResolvable()));
 }

 bool RenderBox::isUnsplittableForPagination() const
 {
     return isReplaced()
         || hasUnsplittableScrollingOverflow()
         || (parent() && isWritingModeRoot())
         || (isFloating() && style().styleType() == PseudoId::FirstLetter && style().initialLetterDrop() > 0);
 }

 LayoutUnit RenderBox::lineHeight(bool /*firstLine*/, LineDirectionMode direction, LinePositionMode /*linePositionMode*/) const
 {
     if (isReplaced())
         return direction == HorizontalLine ? m_marginBox.top() + height() + m_marginBox.bottom() : m_marginBox.right() + width() + m_marginBox.left();
     return 0;
 }

 int RenderBox::baselinePosition(FontBaseline baselineType, bool /*firstLine*/, LineDirectionMode direction, LinePositionMode /*linePositionMode*/) const
 {
     if (isReplaced()) {
         int result = direction == HorizontalLine ? m_marginBox.top() + height() + m_marginBox.bottom() : m_marginBox.right() + width() + m_marginBox.left();
         if (baselineType == AlphabeticBaseline)
             return result;
         return result - result / 2;
     }
     return 0;
 }


 RenderLayer* RenderBox::enclosingFloatPaintingLayer() const
 {
     for (auto& box : lineageOfType<RenderBox>(*this)) {
         if (box.layer() && box.layer()->isSelfPaintingLayer())
             return box.layer();
     }
     return nullptr;
 }

 LayoutRect RenderBox::logicalVisualOverflowRectForPropagation(const RenderStyle* parentStyle) const
 {
     LayoutRect rect = visualOverflowRectForPropagation(parentStyle);
     if (!parentStyle->isHorizontalWritingMode())
         return rect.transposedRect();
     return rect;
 }

 LayoutRect RenderBox::visualOverflowRectForPropagation(const RenderStyle* parentStyle) const
 {
     // If the writing modes of the child and parent match, then we don't have to
     // do anything fancy. Just return the result.
     LayoutRect rect = visualOverflowRect();
     if (parentStyle->writingMode() == style().writingMode())
         return rect;

     // We are putting ourselves into our parent's coordinate space.  If there is a flipped block mismatch
     // in a particular axis, then we have to flip the rect along that axis.
     if (style().writingMode() == RightToLeftWritingMode || parentStyle->writingMode() == RightToLeftWritingMode)
         rect.setX(width() - rect.maxX());
     else if (style().writingMode() == BottomToTopWritingMode || parentStyle->writingMode() == BottomToTopWritingMode)
         rect.setY(height() - rect.maxY());

     return rect;
 }

 LayoutRect RenderBox::logicalLayoutOverflowRectForPropagation(const RenderStyle* parentStyle) const
 {
     LayoutRect rect = layoutOverflowRectForPropagation(parentStyle);
     if (!parentStyle->isHorizontalWritingMode())
         return rect.transposedRect();
     return rect;
 }

 LayoutRect RenderBox::layoutOverflowRectForPropagation(const RenderStyle* parentStyle) const
 {
     // Only propagate interior layout overflow if we don't clip it.
     LayoutRect rect = borderBoxRect();
     if (!hasOverflowClip())
         rect.unite(layoutOverflowRect());

     bool hasTransform = this->hasTransform();
     if (isInFlowPositioned() || hasTransform) {
         // If we are relatively positioned or if we have a transform, then we have to convert
         // this rectangle into physical coordinates, apply relative positioning and transforms
         // to it, and then convert it back.
         flipForWritingMode(rect);

         if (hasTransform)
             rect = layer()->currentTransform().mapRect(rect);

         if (isInFlowPositioned())
             rect.move(offsetForInFlowPosition());

         // Now we need to flip back.
         flipForWritingMode(rect);
     }

     // If the writing modes of the child and parent match, then we don't have to
     // do anything fancy. Just return the result.
     if (parentStyle->writingMode() == style().writingMode())
         return rect;

     // We are putting ourselves into our parent's coordinate space.  If there is a flipped block mismatch
     // in a particular axis, then we have to flip the rect along that axis.
     if (style().writingMode() == RightToLeftWritingMode || parentStyle->writingMode() == RightToLeftWritingMode)
         rect.setX(width() - rect.maxX());
     else if (style().writingMode() == BottomToTopWritingMode || parentStyle->writingMode() == BottomToTopWritingMode)
         rect.setY(height() - rect.maxY());

     return rect;
 }

 LayoutRect RenderBox::flippedClientBoxRect() const
 {
     // Because of the special coordinate system used for overflow rectangles (not quite logical, not
     // quite physical), we need to flip the block progression coordinate in vertical-rl and
     // horizontal-bt writing modes. Apart from that, this method does the same as clientBoxRect().

     LayoutUnit left = borderLeft();
     LayoutUnit top = borderTop();
     LayoutUnit right = borderRight();
     LayoutUnit bottom = borderBottom();
     // Calculate physical padding box.
     LayoutRect rect(left, top, width() - left - right, height() - top - bottom);
     // Flip block progression axis if writing mode is vertical-rl or horizontal-bt.
     flipForWritingMode(rect);
     // Subtract space occupied by scrollbars. They are at their physical edge in this coordinate
     // system, so order is important here: first flip, then subtract scrollbars.
     if (shouldPlaceBlockDirectionScrollbarOnLeft())
         rect.move(verticalScrollbarWidth(), 0);
     rect.contract(verticalScrollbarWidth(), horizontalScrollbarHeight());
     return rect;
 }

 LayoutRect RenderBox::overflowRectForPaintRejection() const
 {
     LayoutRect overflowRect = visualOverflowRect();

     if (!m_overflow || !usesCompositedScrolling())
         return overflowRect;

     overflowRect.unite(layoutOverflowRect());
     overflowRect.moveBy(-scrollPosition());
     return overflowRect;
 }

 LayoutUnit RenderBox::offsetLeft() const
 {
     return adjustedPositionRelativeToOffsetParent(topLeftLocation()).x();
 }

 LayoutUnit RenderBox::offsetTop() const
 {
     return adjustedPositionRelativeToOffsetParent(topLeftLocation()).y();
 }

 LayoutPoint RenderBox::flipForWritingModeForChild(const RenderBox* child, const LayoutPoint& point) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return point;

     // The child is going to add in its x() and y(), so we have to make sure it ends up in
     // the right place.
     if (isHorizontalWritingMode())
         return LayoutPoint(point.x(), point.y() + height() - child->height() - (2 * child->y()));
     return LayoutPoint(point.x() + width() - child->width() - (2 * child->x()), point.y());
 }

 void RenderBox::flipForWritingMode(LayoutRect& rect) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return;

     if (isHorizontalWritingMode())
         rect.setY(height() - rect.maxY());
     else
         rect.setX(width() - rect.maxX());
 }

 LayoutUnit RenderBox::flipForWritingMode(LayoutUnit position) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return position;
     return logicalHeight() - position;
 }

 LayoutPoint RenderBox::flipForWritingMode(const LayoutPoint& position) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return position;
     return isHorizontalWritingMode() ? LayoutPoint(position.x(), height() - position.y()) : LayoutPoint(width() - position.x(), position.y());
 }

 LayoutSize RenderBox::flipForWritingMode(const LayoutSize& offset) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return offset;
     return isHorizontalWritingMode() ? LayoutSize(offset.width(), height() - offset.height()) : LayoutSize(width() - offset.width(), offset.height());
 }

 FloatPoint RenderBox::flipForWritingMode(const FloatPoint& position) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return position;
     return isHorizontalWritingMode() ? FloatPoint(position.x(), height() - position.y()) : FloatPoint(width() - position.x(), position.y());
 }

 void RenderBox::flipForWritingMode(FloatRect& rect) const
 {
     if (!style().isFlippedBlocksWritingMode())
         return;

     if (isHorizontalWritingMode())
         rect.setY(height() - rect.maxY());
     else
         rect.setX(width() - rect.maxX());
 }

 LayoutPoint RenderBox::topLeftLocation() const
 {
     if (!view().frameView().hasFlippedBlockRenderers())
         return location();

     RenderBlock* containerBlock = containingBlock();
     if (!containerBlock || containerBlock == this)
         return location();
     return containerBlock->flipForWritingModeForChild(this, location());
 }

 LayoutSize RenderBox::topLeftLocationOffset() const
 {
     if (!view().frameView().hasFlippedBlockRenderers())
         return locationOffset();

     RenderBlock* containerBlock = containingBlock();
     if (!containerBlock || containerBlock == this)
         return locationOffset();

     LayoutRect rect(frameRect());
     containerBlock->flipForWritingMode(rect); // FIXME: This is wrong if we are an absolutely positioned object enclosed by a relative-positioned inline.
     return LayoutSize(rect.x(), rect.y());
 }

 void RenderBox::applyTopLeftLocationOffsetWithFlipping(LayoutPoint& point) const
 {
     RenderBlock* containerBlock = containingBlock();
     if (!containerBlock || containerBlock == this) {
         point.move(m_frameRect.x(), m_frameRect.y());
         return;
     }

     LayoutRect rect(frameRect());
     containerBlock->flipForWritingMode(rect); // FIXME: This is wrong if we are an absolutely positioned object  enclosed by a relative-positioned inline.
     point.move(rect.x(), rect.y());
 }

 bool RenderBox::hasRelativeDimensions() const
 {
     return style().height().isPercentOrCalculated() || style().width().isPercentOrCalculated()
         || style().maxHeight().isPercentOrCalculated() || style().maxWidth().isPercentOrCalculated()
         || style().minHeight().isPercentOrCalculated() || style().minWidth().isPercentOrCalculated();
 }

 bool RenderBox::hasRelativeLogicalHeight() const
 {
     return style().logicalHeight().isPercentOrCalculated()
         || style().logicalMinHeight().isPercentOrCalculated()
         || style().logicalMaxHeight().isPercentOrCalculated();
 }

 bool RenderBox::hasRelativeLogicalWidth() const
 {
     return style().logicalWidth().isPercentOrCalculated()
         || style().logicalMinWidth().isPercentOrCalculated()
         || style().logicalMaxWidth().isPercentOrCalculated();
 }

 LayoutUnit RenderBox::offsetFromLogicalTopOfFirstPage() const
 {
     auto* layoutState = view().frameView().layoutContext().layoutState();
     if ((layoutState && !layoutState->isPaginated()) || (!layoutState && !enclosingFragmentedFlow()))
         return 0;

     RenderBlock* containerBlock = containingBlock();
     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
 }

 const RenderBox* RenderBox::findEnclosingScrollableContainer() const
 {
     for (auto& candidate : lineageOfType<RenderBox>(*this)) {
         if (candidate.hasOverflowClip())
             return &candidate;
     }
     // If all parent elements are not overflow scrollable, check the body.
     if (document().body() && frame().mainFrame().view() && frame().mainFrame().view()->isScrollable())
         return document().body()->renderBox();

     return nullptr;
 }

 } // namespace WebCore