Source/WebCore/dom/Element.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004-2014 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * 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 "Element.h"

 #include "AXObjectCache.h"
 #include "Attr.h"
 #include "CSSParser.h"
 #include "Chrome.h"
 #include "ChromeClient.h"
 #include "ClientRect.h"
 #include "ClientRectList.h"
 #include "ContainerNodeAlgorithms.h"
 #include "DOMTokenList.h"
 #include "DocumentSharedObjectPool.h"
 #include "ElementIterator.h"
 #include "ElementRareData.h"
 #include "EventDispatcher.h"
 #include "FlowThreadController.h"
 #include "FocusController.h"
 #include "FocusEvent.h"
 #include "FrameSelection.h"
 #include "FrameView.h"
 #include "HTMLCanvasElement.h"
 #include "HTMLCollection.h"
 #include "HTMLDocument.h"
 #include "HTMLFormControlsCollection.h"
 #include "HTMLLabelElement.h"
 #include "HTMLNameCollection.h"
 #include "HTMLOptionsCollection.h"
 #include "HTMLParserIdioms.h"
 #include "HTMLSelectElement.h"
 #include "HTMLTableRowsCollection.h"
 #include "HTMLTemplateElement.h"
 #include "InsertionPoint.h"
 #include "KeyboardEvent.h"
 #include "MutationObserverInterestGroup.h"
 #include "MutationRecord.h"
 #include "NodeRenderStyle.h"
 #include "PlatformWheelEvent.h"
 #include "PointerLockController.h"
 #include "RenderLayer.h"
 #include "RenderNamedFlowFragment.h"
 #include "RenderRegion.h"
 #include "RenderTheme.h"
 #include "RenderView.h"
 #include "RenderWidget.h"
 #include "SVGDocumentExtensions.h"
 #include "SVGElement.h"
 #include "SVGNames.h"
 #include "SelectorQuery.h"
 #include "Settings.h"
 #include "StyleProperties.h"
 #include "StyleResolver.h"
 #include "TextIterator.h"
 #include "VoidCallback.h"
 #include "WheelEvent.h"
 #include "XLinkNames.h"
 #include "XMLNSNames.h"
 #include "XMLNames.h"
 #include "htmlediting.h"
 #include "markup.h"
 #include <wtf/BitVector.h>
 #include <wtf/CurrentTime.h>
 #include <wtf/text/CString.h>

 namespace WebCore {

 using namespace HTMLNames;
 using namespace XMLNames;

 static inline bool shouldIgnoreAttributeCase(const Element& element)
 {
     return element.isHTMLElement() && element.document().isHTMLDocument();
 }

 static HashMap<Element*, Vector<RefPtr<Attr>>>& attrNodeListMap()
 {
     static NeverDestroyed<HashMap<Element*, Vector<RefPtr<Attr>>>> map;
     return map;
 }

 static Vector<RefPtr<Attr>>* attrNodeListForElement(Element& element)
 {
     if (!element.hasSyntheticAttrChildNodes())
         return nullptr;
     ASSERT(attrNodeListMap().contains(&element));
     return &attrNodeListMap().find(&element)->value;
 }

 static Vector<RefPtr<Attr>>& ensureAttrNodeListForElement(Element& element)
 {
     if (element.hasSyntheticAttrChildNodes()) {
         ASSERT(attrNodeListMap().contains(&element));
         return attrNodeListMap().find(&element)->value;
     }
     ASSERT(!attrNodeListMap().contains(&element));
     element.setHasSyntheticAttrChildNodes(true);
     return attrNodeListMap().add(&element, Vector<RefPtr<Attr>>()).iterator->value;
 }

 static void removeAttrNodeListForElement(Element& element)
 {
     ASSERT(element.hasSyntheticAttrChildNodes());
     ASSERT(attrNodeListMap().contains(&element));
     attrNodeListMap().remove(&element);
     element.setHasSyntheticAttrChildNodes(false);
 }

 static Attr* findAttrNodeInList(Vector<RefPtr<Attr>>& attrNodeList, const QualifiedName& name)
 {
     for (auto& node : attrNodeList) {
         if (node->qualifiedName() == name)
             return node.get();
     }
     return nullptr;
 }

 Ref<Element> Element::create(const QualifiedName& tagName, Document& document)
 {
     return adoptRef(*new Element(tagName, document, CreateElement));
 }

 Element::Element(const QualifiedName& tagName, Document& document, ConstructionType type)
     : ContainerNode(document, type)
     , m_tagName(tagName)
 {
 }

 Element::~Element()
 {
 #ifndef NDEBUG
     if (document().hasLivingRenderTree()) {
         // When the document is not destroyed, an element that was part of a named flow
         // content nodes should have been removed from the content nodes collection
         // and the isNamedFlowContentNode flag reset.
         ASSERT_WITH_SECURITY_IMPLICATION(!isNamedFlowContentNode());
     }
 #endif

     ASSERT(!beforePseudoElement());
     ASSERT(!afterPseudoElement());

     removeShadowRoot();

     if (hasSyntheticAttrChildNodes())
         detachAllAttrNodesFromElement();

     if (hasPendingResources()) {
         document().accessSVGExtensions().removeElementFromPendingResources(this);
         ASSERT(!hasPendingResources());
     }
 }

 inline ElementRareData* Element::elementRareData() const
 {
     ASSERT_WITH_SECURITY_IMPLICATION(hasRareData());
     return static_cast<ElementRareData*>(rareData());
 }

 inline ElementRareData& Element::ensureElementRareData()
 {
     return static_cast<ElementRareData&>(ensureRareData());
 }

 void Element::clearTabIndexExplicitlyIfNeeded()
 {
     if (hasRareData())
         elementRareData()->clearTabIndexExplicitly();
 }

 void Element::setTabIndexExplicitly(short tabIndex)
 {
     ensureElementRareData().setTabIndexExplicitly(tabIndex);
 }

 bool Element::supportsFocus() const
 {
     return hasRareData() && elementRareData()->tabIndexSetExplicitly();
 }

 Element* Element::focusDelegate()
 {
     return this;
 }

 short Element::tabIndex() const
 {
     return hasRareData() ? elementRareData()->tabIndex() : 0;
 }

 void Element::setTabIndex(int value)
 {
     setIntegralAttribute(tabindexAttr, value);
 }

 bool Element::isKeyboardFocusable(KeyboardEvent*) const
 {
     return isFocusable() && tabIndex() >= 0;
 }

 bool Element::isMouseFocusable() const
 {
     return isFocusable();
 }

 bool Element::shouldUseInputMethod()
 {
     return isContentEditable(UserSelectAllIsAlwaysNonEditable);
 }

 bool Element::dispatchMouseEvent(const PlatformMouseEvent& platformEvent, const AtomicString& eventType, int detail, Element* relatedTarget)
 {
     if (isDisabledFormControl())
         return false;

     RefPtr<MouseEvent> mouseEvent = MouseEvent::create(eventType, document().defaultView(), platformEvent, detail, relatedTarget);

     if (mouseEvent->type().isEmpty())
         return true; // Shouldn't happen.

     ASSERT(!mouseEvent->target() || mouseEvent->target() != relatedTarget);
     bool didNotSwallowEvent = dispatchEvent(mouseEvent) && !mouseEvent->defaultHandled();

     if (mouseEvent->type() == eventNames().clickEvent && mouseEvent->detail() == 2) {
         // Special case: If it's a double click event, we also send the dblclick event. This is not part
         // of the DOM specs, but is used for compatibility with the ondblclick="" attribute. This is treated
         // as a separate event in other DOM-compliant browsers like Firefox, and so we do the same.
         RefPtr<MouseEvent> doubleClickEvent = MouseEvent::create();
         doubleClickEvent->initMouseEvent(eventNames().dblclickEvent,
             mouseEvent->bubbles(), mouseEvent->cancelable(), mouseEvent->view(), mouseEvent->detail(),
             mouseEvent->screenX(), mouseEvent->screenY(), mouseEvent->clientX(), mouseEvent->clientY(),
             mouseEvent->ctrlKey(), mouseEvent->altKey(), mouseEvent->shiftKey(), mouseEvent->metaKey(),
             mouseEvent->button(), relatedTarget);

         if (mouseEvent->defaultHandled())
             doubleClickEvent->setDefaultHandled();

         dispatchEvent(doubleClickEvent);
         if (doubleClickEvent->defaultHandled() || doubleClickEvent->defaultPrevented())
             return false;
     }
     return didNotSwallowEvent;
 }


 bool Element::dispatchWheelEvent(const PlatformWheelEvent& event)
 {
     RefPtr<WheelEvent> wheelEvent = WheelEvent::create(event, document().defaultView());
     return EventDispatcher::dispatchEvent(this, wheelEvent) && !wheelEvent->defaultHandled();
 }

 bool Element::dispatchKeyEvent(const PlatformKeyboardEvent& platformEvent)
 {
     RefPtr<KeyboardEvent> event = KeyboardEvent::create(platformEvent, document().defaultView());
     return EventDispatcher::dispatchEvent(this, event) && !event->defaultHandled();
 }

 void Element::dispatchSimulatedClick(Event* underlyingEvent, SimulatedClickMouseEventOptions eventOptions, SimulatedClickVisualOptions visualOptions)
 {
     EventDispatcher::dispatchSimulatedClick(this, underlyingEvent, eventOptions, visualOptions);
 }

 DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, blur);
 DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, error);
 DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, focus);
 DEFINE_VIRTUAL_ATTRIBUTE_EVENT_LISTENER(Element, load);

 RefPtr<Node> Element::cloneNodeInternal(Document& targetDocument, CloningOperation type)
 {
     switch (type) {
     case CloningOperation::OnlySelf:
     case CloningOperation::SelfWithTemplateContent:
         return cloneElementWithoutChildren(targetDocument);
     case CloningOperation::Everything:
         return cloneElementWithChildren(targetDocument);
     }
     ASSERT_NOT_REACHED();
     return nullptr;
 }

 RefPtr<Element> Element::cloneElementWithChildren(Document& targetDocument)
 {
     RefPtr<Element> clone = cloneElementWithoutChildren(targetDocument);
     cloneChildNodes(clone.get());
     return clone.release();
 }

 RefPtr<Element> Element::cloneElementWithoutChildren(Document& targetDocument)
 {
     RefPtr<Element> clone = cloneElementWithoutAttributesAndChildren(targetDocument);
     // This will catch HTML elements in the wrong namespace that are not correctly copied.
     // This is a sanity check as HTML overloads some of the DOM methods.
     ASSERT(isHTMLElement() == clone->isHTMLElement());

     clone->cloneDataFromElement(*this);
     return clone.release();
 }

 RefPtr<Element> Element::cloneElementWithoutAttributesAndChildren(Document& targetDocument)
 {
     return targetDocument.createElement(tagQName(), false);
 }

 RefPtr<Attr> Element::detachAttribute(unsigned index)
 {
     ASSERT(elementData());

     const Attribute& attribute = elementData()->attributeAt(index);

     RefPtr<Attr> attrNode = attrIfExists(attribute.name());
     if (attrNode)
         detachAttrNodeFromElementWithValue(attrNode.get(), attribute.value());
     else
         attrNode = Attr::create(document(), attribute.name(), attribute.value());

     removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
     return attrNode.release();
 }

 bool Element::removeAttribute(const QualifiedName& name)
 {
     if (!elementData())
         return false;

     unsigned index = elementData()->findAttributeIndexByName(name);
     if (index == ElementData::attributeNotFound)
         return false;

     removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
     return true;
 }

 void Element::setBooleanAttribute(const QualifiedName& name, bool value)
 {
     if (value)
         setAttribute(name, emptyAtom);
     else
         removeAttribute(name);
 }

 NamedNodeMap& Element::attributes() const
 {
     ElementRareData& rareData = const_cast<Element*>(this)->ensureElementRareData();
     if (NamedNodeMap* attributeMap = rareData.attributeMap())
         return *attributeMap;

     rareData.setAttributeMap(NamedNodeMap::create(const_cast<Element&>(*this)));
     return *rareData.attributeMap();
 }

 Node::NodeType Element::nodeType() const
 {
     return ELEMENT_NODE;
 }

 bool Element::hasAttribute(const QualifiedName& name) const
 {
     return hasAttributeNS(name.namespaceURI(), name.localName());
 }

 void Element::synchronizeAllAttributes() const
 {
     if (!elementData())
         return;
     if (elementData()->styleAttributeIsDirty()) {
         ASSERT(isStyledElement());
         static_cast<const StyledElement*>(this)->synchronizeStyleAttributeInternal();
     }

     if (elementData()->animatedSVGAttributesAreDirty()) {
         ASSERT(isSVGElement());
         downcast<SVGElement>(*this).synchronizeAnimatedSVGAttribute(anyQName());
     }
 }

 ALWAYS_INLINE void Element::synchronizeAttribute(const QualifiedName& name) const
 {
     if (!elementData())
         return;
     if (UNLIKELY(name == styleAttr && elementData()->styleAttributeIsDirty())) {
         ASSERT_WITH_SECURITY_IMPLICATION(isStyledElement());
         static_cast<const StyledElement*>(this)->synchronizeStyleAttributeInternal();
         return;
     }

     if (UNLIKELY(elementData()->animatedSVGAttributesAreDirty())) {
         ASSERT(isSVGElement());
         downcast<SVGElement>(*this).synchronizeAnimatedSVGAttribute(name);
     }
 }

 ALWAYS_INLINE void Element::synchronizeAttribute(const AtomicString& localName) const
 {
     // This version of synchronizeAttribute() is streamlined for the case where you don't have a full QualifiedName,
     // e.g when called from DOM API.
     if (!elementData())
         return;
     if (elementData()->styleAttributeIsDirty() && equalPossiblyIgnoringCase(localName, styleAttr.localName(), shouldIgnoreAttributeCase(*this))) {
         ASSERT_WITH_SECURITY_IMPLICATION(isStyledElement());
         static_cast<const StyledElement*>(this)->synchronizeStyleAttributeInternal();
         return;
     }

     if (elementData()->animatedSVGAttributesAreDirty()) {
         // We're not passing a namespace argument on purpose. SVGNames::*Attr are defined w/o namespaces as well.
         ASSERT_WITH_SECURITY_IMPLICATION(isSVGElement());
         downcast<SVGElement>(*this).synchronizeAnimatedSVGAttribute(QualifiedName(nullAtom, localName, nullAtom));
     }
 }

 const AtomicString& Element::getAttribute(const QualifiedName& name) const
 {
     if (!elementData())
         return nullAtom;
     synchronizeAttribute(name);
     if (const Attribute* attribute = findAttributeByName(name))
         return attribute->value();
     return nullAtom;
 }

 bool Element::isFocusable() const
 {
     if (!inDocument() || !supportsFocus())
         return false;

     if (!renderer()) {
         // If the node is in a display:none tree it might say it needs style recalc but
         // the whole document is actually up to date.
         ASSERT(!needsStyleRecalc() || !document().childNeedsStyleRecalc());

         // Elements in canvas fallback content are not rendered, but they are allowed to be
         // focusable as long as their canvas is displayed and visible.
         if (auto* canvas = ancestorsOfType<HTMLCanvasElement>(*this).first())
             return canvas->renderer() && canvas->renderer()->style().visibility() == VISIBLE;
     }

     // FIXME: Even if we are not visible, we might have a child that is visible.
     // Hyatt wants to fix that some day with a "has visible content" flag or the like.
     if (!renderer() || renderer()->style().visibility() != VISIBLE)
         return false;

     return true;
 }

 bool Element::isUserActionElementInActiveChain() const
 {
     ASSERT(isUserActionElement());
     return document().userActionElements().isInActiveChain(this);
 }

 bool Element::isUserActionElementActive() const
 {
     ASSERT(isUserActionElement());
     return document().userActionElements().isActive(this);
 }

 bool Element::isUserActionElementFocused() const
 {
     ASSERT(isUserActionElement());
     return document().userActionElements().isFocused(this);
 }

 bool Element::isUserActionElementHovered() const
 {
     ASSERT(isUserActionElement());
     return document().userActionElements().isHovered(this);
 }

 void Element::setActive(bool flag, bool pause)
 {
     if (flag == active())
         return;

     document().userActionElements().setActive(this, flag);

     if (!renderer())
         return;

     bool reactsToPress = renderStyle()->affectedByActive() || childrenAffectedByActive();
     if (reactsToPress)
         setNeedsStyleRecalc();

     if (renderer()->style().hasAppearance() && renderer()->theme().stateChanged(*renderer(), ControlStates::PressedState))
         reactsToPress = true;

     // The rest of this function implements a feature that only works if the
     // platform supports immediate invalidations on the ChromeClient, so bail if
     // that isn't supported.
     if (!document().page()->chrome().client().supportsImmediateInvalidation())
         return;

     if (reactsToPress && pause) {
         // The delay here is subtle. It relies on an assumption, namely that the amount of time it takes
         // to repaint the "down" state of the control is about the same time as it would take to repaint the
         // "up" state. Once you assume this, you can just delay for 100ms - that time (assuming that after you
         // leave this method, it will be about that long before the flush of the up state happens again).
 #ifdef HAVE_FUNC_USLEEP
         double startTime = monotonicallyIncreasingTime();
 #endif

         document().updateStyleIfNeeded();

         // Do an immediate repaint.
         if (renderer())
             renderer()->repaint();

         // FIXME: Come up with a less ridiculous way of doing this.
 #ifdef HAVE_FUNC_USLEEP
         // Now pause for a small amount of time (1/10th of a second from before we repainted in the pressed state)
         double remainingTime = 0.1 - (monotonicallyIncreasingTime() - startTime);
         if (remainingTime > 0)
             usleep(static_cast<useconds_t>(remainingTime * 1000000.0));
 #endif
     }
 }

 void Element::setFocus(bool flag)
 {
     if (flag == focused())
         return;

     document().userActionElements().setFocused(this, flag);
     setNeedsStyleRecalc();
 }

 void Element::setHovered(bool flag)
 {
     if (flag == hovered())
         return;

     document().userActionElements().setHovered(this, flag);

     if (!renderer()) {
         // When setting hover to false, the style needs to be recalc'd even when
         // there's no renderer (imagine setting display:none in the :hover class,
         // if a nil renderer would prevent this element from recalculating its
         // style, it would never go back to its normal style and remain
         // stuck in its hovered style).
         if (!flag)
             setNeedsStyleRecalc();

         return;
     }

     if (renderer()->style().affectedByHover() || childrenAffectedByHover())
         setNeedsStyleRecalc();

     if (renderer()->style().hasAppearance())
         renderer()->theme().stateChanged(*renderer(), ControlStates::HoverState);
 }

 void Element::scrollIntoView(bool alignToTop)
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (!renderer())
         return;

     LayoutRect bounds = renderer()->anchorRect();
     // Align to the top / bottom and to the closest edge.
     if (alignToTop)
         renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignTopAlways);
     else
         renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignBottomAlways);
 }

 void Element::scrollIntoViewIfNeeded(bool centerIfNeeded)
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (!renderer())
         return;

     LayoutRect bounds = renderer()->anchorRect();
     if (centerIfNeeded)
         renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignCenterIfNeeded, ScrollAlignment::alignCenterIfNeeded);
     else
         renderer()->scrollRectToVisible(bounds, ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignToEdgeIfNeeded);
 }

 void Element::scrollByUnits(int units, ScrollGranularity granularity)
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (!renderer())
         return;

     if (!renderer()->hasOverflowClip())
         return;

     ScrollDirection direction = ScrollDown;
     if (units < 0) {
         direction = ScrollUp;
         units = -units;
     }
     Element* stopElement = this;
     downcast<RenderBox>(*renderer()).scroll(direction, granularity, units, &stopElement);
 }

 void Element::scrollByLines(int lines)
 {
     scrollByUnits(lines, ScrollByLine);
 }

 void Element::scrollByPages(int pages)
 {
     scrollByUnits(pages, ScrollByPage);
 }

 static double localZoomForRenderer(const RenderElement& renderer)
 {
     // FIXME: This does the wrong thing if two opposing zooms are in effect and canceled each
     // other out, but the alternative is that we'd have to crawl up the whole render tree every
     // time (or store an additional bit in the RenderStyle to indicate that a zoom was specified).
     double zoomFactor = 1;
     if (renderer.style().effectiveZoom() != 1) {
         // Need to find the nearest enclosing RenderElement that set up
         // a differing zoom, and then we divide our result by it to eliminate the zoom.
         const RenderElement* prev = &renderer;
         for (RenderElement* curr = prev->parent(); curr; curr = curr->parent()) {
             if (curr->style().effectiveZoom() != prev->style().effectiveZoom()) {
                 zoomFactor = prev->style().zoom();
                 break;
             }
             prev = curr;
         }
         if (prev->isRenderView())
             zoomFactor = prev->style().zoom();
     }
     return zoomFactor;
 }

 static double adjustForLocalZoom(LayoutUnit value, const RenderElement& renderer, double& zoomFactor)
 {
     zoomFactor = localZoomForRenderer(renderer);
     if (zoomFactor == 1)
         return value.toDouble();
     return value.toDouble() / zoomFactor;
 }

 enum LegacyCSSOMElementMetricsRoundingStrategy { Round, Floor };

 static bool subpixelMetricsEnabled(const Document& document)
 {
     return document.settings() && document.settings()->subpixelCSSOMElementMetricsEnabled();
 }

 static double convertToNonSubpixelValueIfNeeded(double value, const Document& document, LegacyCSSOMElementMetricsRoundingStrategy roundStrategy = Round)
 {
     return subpixelMetricsEnabled(document) ? value : roundStrategy == Round ? round(value) : floor(value);
 }

 double Element::offsetLeft()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBoxModelObject* renderer = renderBoxModelObject()) {
         LayoutUnit offsetLeft = subpixelMetricsEnabled(renderer->document()) ? renderer->offsetLeft() : LayoutUnit(renderer->pixelSnappedOffsetLeft());
         double zoomFactor = 1;
         double offsetLeftAdjustedWithZoom = adjustForLocalZoom(offsetLeft, *renderer, zoomFactor);
         return convertToNonSubpixelValueIfNeeded(offsetLeftAdjustedWithZoom, renderer->document(), zoomFactor == 1 ? Floor : Round);
     }
     return 0;
 }

 double Element::offsetTop()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBoxModelObject* renderer = renderBoxModelObject()) {
         LayoutUnit offsetTop = subpixelMetricsEnabled(renderer->document()) ? renderer->offsetTop() : LayoutUnit(renderer->pixelSnappedOffsetTop());
         double zoomFactor = 1;
         double offsetTopAdjustedWithZoom = adjustForLocalZoom(offsetTop, *renderer, zoomFactor);
         return convertToNonSubpixelValueIfNeeded(offsetTopAdjustedWithZoom, renderer->document(), zoomFactor == 1 ? Floor : Round);
     }
     return 0;
 }

 double Element::offsetWidth()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBoxModelObject* renderer = renderBoxModelObject()) {
         LayoutUnit offsetWidth = subpixelMetricsEnabled(renderer->document()) ? renderer->offsetWidth() : LayoutUnit(renderer->pixelSnappedOffsetWidth());
         return convertToNonSubpixelValueIfNeeded(adjustLayoutUnitForAbsoluteZoom(offsetWidth, *renderer).toDouble(), renderer->document());
     }
     return 0;
 }

 double Element::offsetHeight()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBoxModelObject* renderer = renderBoxModelObject()) {
         LayoutUnit offsetHeight = subpixelMetricsEnabled(renderer->document()) ? renderer->offsetHeight() : LayoutUnit(renderer->pixelSnappedOffsetHeight());
         return convertToNonSubpixelValueIfNeeded(adjustLayoutUnitForAbsoluteZoom(offsetHeight, *renderer).toDouble(), renderer->document());
     }
     return 0;
 }

 Element* Element::bindingsOffsetParent()
 {
     Element* element = offsetParent();
     if (!element || !element->isInShadowTree())
         return element;
     return element->containingShadowRoot()->type() == ShadowRoot::UserAgentShadowRoot ? 0 : element;
 }

 Element* Element::offsetParent()
 {
     document().updateLayoutIgnorePendingStylesheets();
     auto renderer = this->renderer();
     if (!renderer)
         return nullptr;
     auto offsetParent = renderer->offsetParent();
     if (!offsetParent)
         return nullptr;
     return offsetParent->element();
 }

 double Element::clientLeft()
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (RenderBox* renderer = renderBox()) {
         LayoutUnit clientLeft = subpixelMetricsEnabled(renderer->document()) ? renderer->clientLeft() : LayoutUnit(roundToInt(renderer->clientLeft()));
         return convertToNonSubpixelValueIfNeeded(adjustLayoutUnitForAbsoluteZoom(clientLeft, *renderer).toDouble(), renderer->document());
     }
     return 0;
 }

 double Element::clientTop()
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (RenderBox* renderer = renderBox()) {
         LayoutUnit clientTop = subpixelMetricsEnabled(renderer->document()) ? renderer->clientTop() : LayoutUnit(roundToInt(renderer->clientTop()));
         return convertToNonSubpixelValueIfNeeded(adjustLayoutUnitForAbsoluteZoom(clientTop, *renderer).toDouble(), renderer->document());
     }
     return 0;
 }

 double Element::clientWidth()
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (!document().hasLivingRenderTree())
         return 0;
     RenderView& renderView = *document().renderView();

     // When in strict mode, clientWidth for the document element should return the width of the containing frame.
     // When in quirks mode, clientWidth for the body element should return the width of the containing frame.
     bool inQuirksMode = document().inQuirksMode();
     if ((!inQuirksMode && document().documentElement() == this) || (inQuirksMode && isHTMLElement() && document().body() == this))
         return adjustForAbsoluteZoom(renderView.frameView().layoutWidth(), renderView);

     if (RenderBox* renderer = renderBox()) {
         LayoutUnit clientWidth = subpixelMetricsEnabled(renderer->document()) ? renderer->clientWidth() : LayoutUnit(renderer->pixelSnappedClientWidth());
         return convertToNonSubpixelValueIfNeeded(adjustLayoutUnitForAbsoluteZoom(clientWidth, *renderer).toDouble(), renderer->document());
     }
     return 0;
 }

 double Element::clientHeight()
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (!document().hasLivingRenderTree())
         return 0;
     RenderView& renderView = *document().renderView();

     // When in strict mode, clientHeight for the document element should return the height of the containing frame.
     // When in quirks mode, clientHeight for the body element should return the height of the containing frame.
     bool inQuirksMode = document().inQuirksMode();
     if ((!inQuirksMode && document().documentElement() == this) || (inQuirksMode && isHTMLElement() && document().body() == this))
         return adjustForAbsoluteZoom(renderView.frameView().layoutHeight(), renderView);

     if (RenderBox* renderer = renderBox()) {
         LayoutUnit clientHeight = subpixelMetricsEnabled(renderer->document()) ? renderer->clientHeight() : LayoutUnit(renderer->pixelSnappedClientHeight());
         return convertToNonSubpixelValueIfNeeded(adjustLayoutUnitForAbsoluteZoom(clientHeight, *renderer).toDouble(), renderer->document());
     }
     return 0;
 }

 int Element::scrollLeft()
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (RenderBox* rend = renderBox())
         return adjustForAbsoluteZoom(rend->scrollLeft(), *rend);
     return 0;
 }

 int Element::scrollTop()
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (RenderBox* rend = renderBox())
         return adjustForAbsoluteZoom(rend->scrollTop(), *rend);
     return 0;
 }

 void Element::setScrollLeft(int newLeft)
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (RenderBox* renderer = renderBox()) {
         renderer->setScrollLeft(static_cast<int>(newLeft * renderer->style().effectiveZoom()));
         if (auto* scrollableArea = renderer->layer())
             scrollableArea->setScrolledProgrammatically(true);
     }
 }

 void Element::setScrollTop(int newTop)
 {
     document().updateLayoutIgnorePendingStylesheets();

     if (RenderBox* renderer = renderBox()) {
         renderer->setScrollTop(static_cast<int>(newTop * renderer->style().effectiveZoom()));
         if (auto* scrollableArea = renderer->layer())
             scrollableArea->setScrolledProgrammatically(true);
     }
 }

 int Element::scrollWidth()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBox* rend = renderBox())
         return adjustForAbsoluteZoom(rend->scrollWidth(), *rend);
     return 0;
 }

 int Element::scrollHeight()
 {
     document().updateLayoutIgnorePendingStylesheets();
     if (RenderBox* rend = renderBox())
         return adjustForAbsoluteZoom(rend->scrollHeight(), *rend);
     return 0;
 }

 IntRect Element::boundsInRootViewSpace()
 {
     document().updateLayoutIgnorePendingStylesheets();

     FrameView* view = document().view();
     if (!view)
         return IntRect();

     Vector<FloatQuad> quads;

     if (isSVGElement() && renderer()) {
         // Get the bounding rectangle from the SVG model.
         SVGElement& svgElement = downcast<SVGElement>(*this);
         FloatRect localRect;
         if (svgElement.getBoundingBox(localRect))
             quads.append(renderer()->localToAbsoluteQuad(localRect));
     } else {
         // Get the bounding rectangle from the box model.
         if (renderBoxModelObject())
             renderBoxModelObject()->absoluteQuads(quads);
     }

     if (quads.isEmpty())
         return IntRect();

     IntRect result = quads[0].enclosingBoundingBox();
     for (size_t i = 1; i < quads.size(); ++i)
         result.unite(quads[i].enclosingBoundingBox());

     result = view->contentsToRootView(result);
     return result;
 }

 Ref<ClientRectList> Element::getClientRects()
 {
     document().updateLayoutIgnorePendingStylesheets();

     RenderBoxModelObject* renderBoxModelObject = this->renderBoxModelObject();
     if (!renderBoxModelObject)
         return ClientRectList::create();

     // FIXME: Handle SVG elements.
     // FIXME: Handle table/inline-table with a caption.

     Vector<FloatQuad> quads;
     renderBoxModelObject->absoluteQuads(quads);
     document().adjustFloatQuadsForScrollAndAbsoluteZoomAndFrameScale(quads, renderBoxModelObject->style());
     return ClientRectList::create(quads);
 }

 Ref<ClientRect> Element::getBoundingClientRect()
 {
     document().updateLayoutIgnorePendingStylesheets();

     Vector<FloatQuad> quads;
     if (isSVGElement() && renderer() && !renderer()->isSVGRoot()) {
         // Get the bounding rectangle from the SVG model.
         SVGElement& svgElement = downcast<SVGElement>(*this);
         FloatRect localRect;
         if (svgElement.getBoundingBox(localRect))
             quads.append(renderer()->localToAbsoluteQuad(localRect));
     } else {
         // Get the bounding rectangle from the box model.
         if (renderBoxModelObject())
             renderBoxModelObject()->absoluteQuads(quads);
     }

     if (quads.isEmpty())
         return ClientRect::create();

     FloatRect result = quads[0].boundingBox();
     for (size_t i = 1; i < quads.size(); ++i)
         result.unite(quads[i].boundingBox());

     document().adjustFloatRectForScrollAndAbsoluteZoomAndFrameScale(result, renderer()->style());
     return ClientRect::create(result);
 }

 IntRect Element::clientRect() const
 {
     if (RenderObject* renderer = this->renderer())
         return document().view()->contentsToRootView(renderer->absoluteBoundingBoxRect());
     return IntRect();
 }

 IntRect Element::screenRect() const
 {
     if (RenderObject* renderer = this->renderer())
         return document().view()->contentsToScreen(renderer->absoluteBoundingBoxRect());
     return IntRect();
 }

 const AtomicString& Element::getAttribute(const AtomicString& localName) const
 {
     if (!elementData())
         return nullAtom;
     synchronizeAttribute(localName);
     if (const Attribute* attribute = elementData()->findAttributeByName(localName, shouldIgnoreAttributeCase(*this)))
         return attribute->value();
     return nullAtom;
 }

 const AtomicString& Element::getAttributeNS(const AtomicString& namespaceURI, const AtomicString& localName) const
 {
     return getAttribute(QualifiedName(nullAtom, localName, namespaceURI));
 }

 void Element::setAttribute(const AtomicString& localName, const AtomicString& value, ExceptionCode& ec)
 {
     if (!Document::isValidName(localName)) {
         ec = INVALID_CHARACTER_ERR;
         return;
     }

     synchronizeAttribute(localName);
     const AtomicString& caseAdjustedLocalName = shouldIgnoreAttributeCase(*this) ? localName.lower() : localName;

     unsigned index = elementData() ? elementData()->findAttributeIndexByName(caseAdjustedLocalName, false) : ElementData::attributeNotFound;
     const QualifiedName& qName = index != ElementData::attributeNotFound ? attributeAt(index).name() : QualifiedName(nullAtom, caseAdjustedLocalName, nullAtom);
     setAttributeInternal(index, qName, value, NotInSynchronizationOfLazyAttribute);
 }

 void Element::setAttribute(const QualifiedName& name, const AtomicString& value)
 {
     synchronizeAttribute(name);
     unsigned index = elementData() ? elementData()->findAttributeIndexByName(name) : ElementData::attributeNotFound;
     setAttributeInternal(index, name, value, NotInSynchronizationOfLazyAttribute);
 }

 void Element::setAttributeWithoutSynchronization(const QualifiedName& name, const AtomicString& value)
 {
     unsigned index = elementData() ? elementData()->findAttributeIndexByName(name) : ElementData::attributeNotFound;
     setAttributeInternal(index, name, value, NotInSynchronizationOfLazyAttribute);
 }

 void Element::setSynchronizedLazyAttribute(const QualifiedName& name, const AtomicString& value)
 {
     unsigned index = elementData() ? elementData()->findAttributeIndexByName(name) : ElementData::attributeNotFound;
     setAttributeInternal(index, name, value, InSynchronizationOfLazyAttribute);
 }

 inline void Element::setAttributeInternal(unsigned index, const QualifiedName& name, const AtomicString& newValue, SynchronizationOfLazyAttribute inSynchronizationOfLazyAttribute)
 {
     if (newValue.isNull()) {
         if (index != ElementData::attributeNotFound)
             removeAttributeInternal(index, inSynchronizationOfLazyAttribute);
         return;
     }

     if (index == ElementData::attributeNotFound) {
         addAttributeInternal(name, newValue, inSynchronizationOfLazyAttribute);
         return;
     }

     const Attribute& attribute = attributeAt(index);
     AtomicString oldValue = attribute.value();
     bool valueChanged = newValue != oldValue;
     QualifiedName attributeName = (!inSynchronizationOfLazyAttribute || valueChanged) ? attribute.name() : name;

     if (!inSynchronizationOfLazyAttribute)
         willModifyAttribute(attributeName, oldValue, newValue);

     if (valueChanged) {
         // If there is an Attr node hooked to this attribute, the Attr::setValue() call below
         // will write into the ElementData.
         // FIXME: Refactor this so it makes some sense.
         if (RefPtr<Attr> attrNode = inSynchronizationOfLazyAttribute ? 0 : attrIfExists(attributeName))
             attrNode->setValue(newValue);
         else
             ensureUniqueElementData().attributeAt(index).setValue(newValue);
     }

     if (!inSynchronizationOfLazyAttribute)
         didModifyAttribute(attributeName, oldValue, newValue);
 }

 static inline AtomicString makeIdForStyleResolution(const AtomicString& value, bool inQuirksMode)
 {
     if (inQuirksMode)
         return value.lower();
     return value;
 }

 static bool checkNeedsStyleInvalidationForIdChange(const AtomicString& oldId, const AtomicString& newId, StyleResolver* styleResolver)
 {
     ASSERT(newId != oldId);
     if (!oldId.isEmpty() && styleResolver->hasSelectorForId(oldId))
         return true;
     if (!newId.isEmpty() && styleResolver->hasSelectorForId(newId))
         return true;
     return false;
 }

 void Element::attributeChanged(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue, AttributeModificationReason)
 {
     parseAttribute(name, newValue);

     document().incDOMTreeVersion();

     if (oldValue == newValue)
         return;

     StyleResolver* styleResolver = document().styleResolverIfExists();
     bool testShouldInvalidateStyle = inRenderedDocument() && styleResolver && styleChangeType() < FullStyleChange;
     bool shouldInvalidateStyle = false;

     if (name == HTMLNames::idAttr) {
         AtomicString oldId = elementData()->idForStyleResolution();
         AtomicString newId = makeIdForStyleResolution(newValue, document().inQuirksMode());
         if (newId != oldId) {
             elementData()->setIdForStyleResolution(newId);
             shouldInvalidateStyle = testShouldInvalidateStyle && checkNeedsStyleInvalidationForIdChange(oldId, newId, styleResolver);
         }
     } else if (name == classAttr)
         classAttributeChanged(newValue);
     else if (name == HTMLNames::nameAttr)
         elementData()->setHasNameAttribute(!newValue.isNull());
     else if (name == HTMLNames::pseudoAttr)
         shouldInvalidateStyle |= testShouldInvalidateStyle && isInShadowTree();


     invalidateNodeListAndCollectionCachesInAncestors(&name, this);

     // If there is currently no StyleResolver, we can't be sure that this attribute change won't affect style.
     shouldInvalidateStyle |= !styleResolver;

     if (shouldInvalidateStyle)
         setNeedsStyleRecalc();

     if (AXObjectCache* cache = document().existingAXObjectCache())
         cache->handleAttributeChanged(name, this);
 }

 template <typename CharacterType>
 static inline bool classStringHasClassName(const CharacterType* characters, unsigned length)
 {
     ASSERT(length > 0);

     unsigned i = 0;
     do {
         if (isNotHTMLSpace(characters[i]))
             break;
         ++i;
     } while (i < length);

     return i < length;
 }

 static inline bool classStringHasClassName(const AtomicString& newClassString)
 {
     unsigned length = newClassString.length();

     if (!length)
         return false;

     if (newClassString.is8Bit())
         return classStringHasClassName(newClassString.characters8(), length);
     return classStringHasClassName(newClassString.characters16(), length);
 }

 static bool checkSelectorForClassChange(const SpaceSplitString& changedClasses, const StyleResolver& styleResolver)
 {
     unsigned changedSize = changedClasses.size();
     for (unsigned i = 0; i < changedSize; ++i) {
         if (styleResolver.hasSelectorForClass(changedClasses[i]))
             return true;
     }
     return false;
 }

 static bool checkSelectorForClassChange(const SpaceSplitString& oldClasses, const SpaceSplitString& newClasses, const StyleResolver& styleResolver)
 {
     unsigned oldSize = oldClasses.size();
     if (!oldSize)
         return checkSelectorForClassChange(newClasses, styleResolver);
     BitVector remainingClassBits;
     remainingClassBits.ensureSize(oldSize);
     // Class vectors tend to be very short. This is faster than using a hash table.
     unsigned newSize = newClasses.size();
     for (unsigned i = 0; i < newSize; ++i) {
         bool foundFromBoth = false;
         for (unsigned j = 0; j < oldSize; ++j) {
             if (newClasses[i] == oldClasses[j]) {
                 remainingClassBits.quickSet(j);
                 foundFromBoth = true;
             }
         }
         if (foundFromBoth)
             continue;
         if (styleResolver.hasSelectorForClass(newClasses[i]))
             return true;
     }
     for (unsigned i = 0; i < oldSize; ++i) {
         // If the bit is not set the the corresponding class has been removed.
         if (remainingClassBits.quickGet(i))
             continue;
         if (styleResolver.hasSelectorForClass(oldClasses[i]))
             return true;
     }
     return false;
 }

 void Element::classAttributeChanged(const AtomicString& newClassString)
 {
     StyleResolver* styleResolver = document().styleResolverIfExists();
     bool testShouldInvalidateStyle = inRenderedDocument() && styleResolver && styleChangeType() < FullStyleChange;
     bool shouldInvalidateStyle = false;

     if (classStringHasClassName(newClassString)) {
         const bool shouldFoldCase = document().inQuirksMode();
         // Note: We'll need ElementData, but it doesn't have to be UniqueElementData.
         if (!elementData())
             ensureUniqueElementData();
         const SpaceSplitString oldClasses = elementData()->classNames();
         elementData()->setClass(newClassString, shouldFoldCase);
         const SpaceSplitString& newClasses = elementData()->classNames();
         shouldInvalidateStyle = testShouldInvalidateStyle && checkSelectorForClassChange(oldClasses, newClasses, *styleResolver);
     } else if (elementData()) {
         const SpaceSplitString& oldClasses = elementData()->classNames();
         shouldInvalidateStyle = testShouldInvalidateStyle && checkSelectorForClassChange(oldClasses, *styleResolver);
         elementData()->clearClass();
     }

     if (hasRareData())
         elementRareData()->clearClassListValueForQuirksMode();

     if (shouldInvalidateStyle)
         setNeedsStyleRecalc();
 }

 URL Element::absoluteLinkURL() const
 {
     if (!isLink())
         return URL();

     AtomicString linkAttribute;
     if (hasTagName(SVGNames::aTag))
         linkAttribute = getAttribute(XLinkNames::hrefAttr);
     else
         linkAttribute = getAttribute(HTMLNames::hrefAttr);

     if (linkAttribute.isEmpty())
         return URL();

     return document().completeURL(stripLeadingAndTrailingHTMLSpaces(linkAttribute));
 }

 WeakPtr<Element> Element::createWeakPtr()
 {
     return ensureElementRareData().weakPtrFactory().createWeakPtr();
 }

 // Returns true is the given attribute is an event handler.
 // We consider an event handler any attribute that begins with "on".
 // It is a simple solution that has the advantage of not requiring any
 // code or configuration change if a new event handler is defined.

 static inline bool isEventHandlerAttribute(const Attribute& attribute)
 {
     return attribute.name().namespaceURI().isNull() && attribute.name().localName().startsWith("on");
 }

 bool Element::isJavaScriptURLAttribute(const Attribute& attribute) const
 {
     return isURLAttribute(attribute) && protocolIsJavaScript(stripLeadingAndTrailingHTMLSpaces(attribute.value()));
 }

 void Element::stripScriptingAttributes(Vector<Attribute>& attributeVector) const
 {
     size_t destination = 0;
     for (size_t source = 0; source < attributeVector.size(); ++source) {
         if (isEventHandlerAttribute(attributeVector[source])
             || isJavaScriptURLAttribute(attributeVector[source])
             || isHTMLContentAttribute(attributeVector[source]))
             continue;

         if (source != destination)
             attributeVector[destination] = attributeVector[source];

         ++destination;
     }
     attributeVector.shrink(destination);
 }

 void Element::parserSetAttributes(const Vector<Attribute>& attributeVector)
 {
     ASSERT(!inDocument());
     ASSERT(!parentNode());
     ASSERT(!m_elementData);

     if (!attributeVector.isEmpty()) {
         if (document().sharedObjectPool())
             m_elementData = document().sharedObjectPool()->cachedShareableElementDataWithAttributes(attributeVector);
         else
             m_elementData = ShareableElementData::createWithAttributes(attributeVector);

     }

     parserDidSetAttributes();

     // Use attributeVector instead of m_elementData because attributeChanged might modify m_elementData.
     for (const auto& attribute : attributeVector)
         attributeChanged(attribute.name(), nullAtom, attribute.value(), ModifiedDirectly);
 }

 void Element::parserDidSetAttributes()
 {
 }

 bool Element::hasAttributes() const
 {
     synchronizeAllAttributes();
     return elementData() && elementData()->length();
 }

 bool Element::hasEquivalentAttributes(const Element* other) const
 {
     synchronizeAllAttributes();
     other->synchronizeAllAttributes();
     if (elementData() == other->elementData())
         return true;
     if (elementData())
         return elementData()->isEquivalent(other->elementData());
     if (other->elementData())
         return other->elementData()->isEquivalent(elementData());
     return true;
 }

 String Element::nodeName() const
 {
     return m_tagName.toString();
 }

 String Element::nodeNamePreservingCase() const
 {
     return m_tagName.toString();
 }

 void Element::setPrefix(const AtomicString& prefix, ExceptionCode& ec)
 {
     ec = 0;
     checkSetPrefix(prefix, ec);
     if (ec)
         return;

     m_tagName.setPrefix(prefix.isEmpty() ? AtomicString() : prefix);
 }

 URL Element::baseURI() const
 {
     const AtomicString& baseAttribute = getAttribute(baseAttr);
     URL base(URL(), baseAttribute);
     if (!base.protocol().isEmpty())
         return base;

     ContainerNode* parent = parentNode();
     if (!parent)
         return base;

     const URL& parentBase = parent->baseURI();
     if (parentBase.isNull())
         return base;

     return URL(parentBase, baseAttribute);
 }

 const AtomicString& Element::imageSourceURL() const
 {
     return fastGetAttribute(srcAttr);
 }

 bool Element::rendererIsNeeded(const RenderStyle& style)
 {
     return style.display() != NONE;
 }

 RenderPtr<RenderElement> Element::createElementRenderer(Ref<RenderStyle>&& style)
 {
     return RenderElement::createFor(*this, WTF::move(style));
 }

 Node::InsertionNotificationRequest Element::insertedInto(ContainerNode& insertionPoint)
 {
     bool wasInDocument = inDocument();
     // need to do superclass processing first so inDocument() is true
     // by the time we reach updateId
     ContainerNode::insertedInto(insertionPoint);
     ASSERT(!wasInDocument || inDocument());

 #if ENABLE(FULLSCREEN_API)
     if (containsFullScreenElement() && parentElement() && !parentElement()->containsFullScreenElement())
         setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(true);
 #endif

     if (!insertionPoint.isInTreeScope())
         return InsertionDone;

     if (hasRareData())
         elementRareData()->clearClassListValueForQuirksMode();

     TreeScope* newScope = &insertionPoint.treeScope();
     HTMLDocument* newDocument = !wasInDocument && inDocument() && is<HTMLDocument>(newScope->documentScope()) ? &downcast<HTMLDocument>(newScope->documentScope()) : nullptr;
     if (newScope != &treeScope())
         newScope = nullptr;

     const AtomicString& idValue = getIdAttribute();
     if (!idValue.isNull()) {
         if (newScope)
             updateIdForTreeScope(*newScope, nullAtom, idValue);
         if (newDocument)
             updateIdForDocument(*newDocument, nullAtom, idValue, AlwaysUpdateHTMLDocumentNamedItemMaps);
     }

     const AtomicString& nameValue = getNameAttribute();
     if (!nameValue.isNull()) {
         if (newScope)
             updateNameForTreeScope(*newScope, nullAtom, nameValue);
         if (newDocument)
             updateNameForDocument(*newDocument, nullAtom, nameValue);
     }

     if (newScope && hasTagName(labelTag)) {
         if (newScope->shouldCacheLabelsByForAttribute())
             updateLabel(*newScope, nullAtom, fastGetAttribute(forAttr));
     }

     return InsertionDone;
 }

 void Element::removedFrom(ContainerNode& insertionPoint)
 {
 #if ENABLE(FULLSCREEN_API)
     if (containsFullScreenElement())
         setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(false);
 #endif
 #if ENABLE(POINTER_LOCK)
     if (document().page())
         document().page()->pointerLockController().elementRemoved(this);
 #endif

     setSavedLayerScrollOffset(IntSize());

     if (insertionPoint.isInTreeScope()) {
         TreeScope* oldScope = &insertionPoint.treeScope();
         HTMLDocument* oldDocument = inDocument() && is<HTMLDocument>(oldScope->documentScope()) ? &downcast<HTMLDocument>(oldScope->documentScope()) : nullptr;
         if (oldScope != &treeScope() || !isInTreeScope())
             oldScope = nullptr;

         const AtomicString& idValue = getIdAttribute();
         if (!idValue.isNull()) {
             if (oldScope)
                 updateIdForTreeScope(*oldScope, idValue, nullAtom);
             if (oldDocument)
                 updateIdForDocument(*oldDocument, idValue, nullAtom, AlwaysUpdateHTMLDocumentNamedItemMaps);
         }

         const AtomicString& nameValue = getNameAttribute();
         if (!nameValue.isNull()) {
             if (oldScope)
                 updateNameForTreeScope(*oldScope, nameValue, nullAtom);
             if (oldDocument)
                 updateNameForDocument(*oldDocument, nameValue, nullAtom);
         }

         if (oldScope && hasTagName(labelTag)) {
             if (oldScope->shouldCacheLabelsByForAttribute())
                 updateLabel(*oldScope, fastGetAttribute(forAttr), nullAtom);
         }
     }

     ContainerNode::removedFrom(insertionPoint);

     if (hasPendingResources())
         document().accessSVGExtensions().removeElementFromPendingResources(this);
 }

 void Element::unregisterNamedFlowContentElement()
 {
     if (document().cssRegionsEnabled() && isNamedFlowContentNode() && document().renderView())
         document().renderView()->flowThreadController().unregisterNamedFlowContentElement(*this);
 }

 ShadowRoot* Element::shadowRoot() const
 {
     return hasRareData() ? elementRareData()->shadowRoot() : 0;
 }

 static bool shouldUseNodeRenderingTraversalSlowPath(const Element& element)
 {
     if (element.isShadowRoot())
         return true;
     return element.isInsertionPoint() || element.shadowRoot();
 }

 void Element::resetNeedsNodeRenderingTraversalSlowPath()
 {
     setNeedsNodeRenderingTraversalSlowPath(shouldUseNodeRenderingTraversalSlowPath(*this));
 }

 void Element::addShadowRoot(Ref<ShadowRoot>&& newShadowRoot)
 {
     ASSERT(!shadowRoot());

     ShadowRoot& shadowRoot = newShadowRoot.get();
     ensureElementRareData().setShadowRoot(WTF::move(newShadowRoot));

     shadowRoot.setHostElement(this);
     shadowRoot.setParentTreeScope(&treeScope());
     shadowRoot.distributor().didShadowBoundaryChange(this);

     ChildNodeInsertionNotifier(*this).notify(shadowRoot);

     resetNeedsNodeRenderingTraversalSlowPath();

     setNeedsStyleRecalc(ReconstructRenderTree);

     InspectorInstrumentation::didPushShadowRoot(*this, shadowRoot);
 }

 void Element::removeShadowRoot()
 {
     RefPtr<ShadowRoot> oldRoot = shadowRoot();
     if (!oldRoot)
         return;
     InspectorInstrumentation::willPopShadowRoot(*this, *oldRoot);
     document().removeFocusedNodeOfSubtree(oldRoot.get());

     ASSERT(!oldRoot->renderer());

     elementRareData()->clearShadowRoot();

     oldRoot->setHostElement(0);
     oldRoot->setParentTreeScope(&document());

     ChildNodeRemovalNotifier(*this).notify(*oldRoot);

     oldRoot->distributor().invalidateDistribution(this);
 }

 RefPtr<ShadowRoot> Element::createShadowRoot(ExceptionCode& ec)
 {
     if (alwaysCreateUserAgentShadowRoot())
         ensureUserAgentShadowRoot();

     ec = HIERARCHY_REQUEST_ERR;
     return nullptr;
 }

 ShadowRoot* Element::userAgentShadowRoot() const
 {
     if (ShadowRoot* shadowRoot = this->shadowRoot()) {
         ASSERT(shadowRoot->type() == ShadowRoot::UserAgentShadowRoot);
         return shadowRoot;
     }
     return nullptr;
 }

 ShadowRoot& Element::ensureUserAgentShadowRoot()
 {
     ShadowRoot* shadowRoot = userAgentShadowRoot();
     if (!shadowRoot) {
         addShadowRoot(ShadowRoot::create(document(), ShadowRoot::UserAgentShadowRoot));
         shadowRoot = userAgentShadowRoot();
         didAddUserAgentShadowRoot(shadowRoot);
     }
     return *shadowRoot;
 }

 const AtomicString& Element::shadowPseudoId() const
 {
     return pseudo();
 }

 bool Element::childTypeAllowed(NodeType type) const
 {
     switch (type) {
     case ELEMENT_NODE:
     case TEXT_NODE:
     case COMMENT_NODE:
     case PROCESSING_INSTRUCTION_NODE:
     case CDATA_SECTION_NODE:
     case ENTITY_REFERENCE_NODE:
         return true;
     default:
         break;
     }
     return false;
 }

 static void checkForEmptyStyleChange(Element& element)
 {
     if (element.styleAffectedByEmpty()) {
         RenderStyle* style = element.renderStyle();
         if (!style || (!style->emptyState() || element.hasChildNodes()))
             element.setNeedsStyleRecalc();
     }
 }

 enum SiblingCheckType { FinishedParsingChildren, SiblingElementRemoved, Other };

 static void checkForSiblingStyleChanges(Element* parent, SiblingCheckType checkType, Element* elementBeforeChange, Element* elementAfterChange)
 {
     // :empty selector.
     checkForEmptyStyleChange(*parent);

     if (parent->styleChangeType() >= FullStyleChange)
         return;

     // :first-child.  In the parser callback case, we don't have to check anything, since we were right the first time.
     // In the DOM case, we only need to do something if |afterChange| is not 0.
     // |afterChange| is 0 in the parser case, so it works out that we'll skip this block.
     if (parent->childrenAffectedByFirstChildRules() && elementAfterChange) {
         // Find our new first child.
         Element* newFirstElement = ElementTraversal::firstChild(parent);
         // Find the first element node following |afterChange|

         // This is the insert/append case.
         if (newFirstElement != elementAfterChange) {
             RenderStyle* style = elementAfterChange->renderStyle();
             if (!style || style->firstChildState())
                 elementAfterChange->setNeedsStyleRecalc();
         }

         // We also have to handle node removal.
         if (checkType == SiblingElementRemoved && newFirstElement == elementAfterChange && newFirstElement) {
             RenderStyle* style = newFirstElement->renderStyle();
             if (!style || !style->firstChildState())
                 newFirstElement->setNeedsStyleRecalc();
         }
     }

     // :last-child.  In the parser callback case, we don't have to check anything, since we were right the first time.
     // In the DOM case, we only need to do something if |afterChange| is not 0.
     if (parent->childrenAffectedByLastChildRules() && elementBeforeChange) {
         // Find our new last child.
         Element* newLastElement = ElementTraversal::lastChild(parent);

         if (newLastElement != elementBeforeChange) {
             RenderStyle* style = elementBeforeChange->renderStyle();
             if (!style || style->lastChildState())
                 elementBeforeChange->setNeedsStyleRecalc();
         }

         // We also have to handle node removal.  The parser callback case is similar to node removal as well in that we need to change the last child
         // to match now.
         if ((checkType == SiblingElementRemoved || checkType == FinishedParsingChildren) && newLastElement == elementBeforeChange && newLastElement) {
             RenderStyle* style = newLastElement->renderStyle();
             if (!style || !style->lastChildState())
                 newLastElement->setNeedsStyleRecalc();
         }
     }

     if (elementAfterChange) {
         if (elementAfterChange->styleIsAffectedByPreviousSibling())
             elementAfterChange->setNeedsStyleRecalc();
         else if (elementAfterChange->affectsNextSiblingElementStyle()) {
             Element* elementToInvalidate = elementAfterChange;
             do {
                 elementToInvalidate = elementToInvalidate->nextElementSibling();
             } while (elementToInvalidate && !elementToInvalidate->styleIsAffectedByPreviousSibling());

             if (elementToInvalidate)
                 elementToInvalidate->setNeedsStyleRecalc();
         }
     }

     // Backward positional selectors include nth-last-child, nth-last-of-type, last-of-type and only-of-type.
     // We have to invalidate everything following the insertion point in the forward case, and everything before the insertion point in the
     // backward case.
     // |afterChange| is 0 in the parser callback case, so we won't do any work for the forward case if we don't have to.
     // For performance reasons we just mark the parent node as changed, since we don't want to make childrenChanged O(n^2) by crawling all our kids
     // here.  recalcStyle will then force a walk of the children when it sees that this has happened.
     if (parent->childrenAffectedByBackwardPositionalRules() && elementBeforeChange)
         parent->setNeedsStyleRecalc();
 }

 void Element::childrenChanged(const ChildChange& change)
 {
     ContainerNode::childrenChanged(change);
     if (change.source == ChildChangeSourceParser)
         checkForEmptyStyleChange(*this);
     else {
         SiblingCheckType checkType = change.type == ElementRemoved ? SiblingElementRemoved : Other;
         checkForSiblingStyleChanges(this, checkType, change.previousSiblingElement, change.nextSiblingElement);
     }

     if (ShadowRoot* shadowRoot = this->shadowRoot())
         shadowRoot->invalidateDistribution();
 }

 void Element::removeAllEventListeners()
 {
     ContainerNode::removeAllEventListeners();
     if (ShadowRoot* shadowRoot = this->shadowRoot())
         shadowRoot->removeAllEventListeners();
 }

 void Element::beginParsingChildren()
 {
     clearIsParsingChildrenFinished();
     if (auto styleResolver = document().styleResolverIfExists())
         styleResolver->pushParentElement(this);
 }

 void Element::finishParsingChildren()
 {
     ContainerNode::finishParsingChildren();
     setIsParsingChildrenFinished();
     checkForSiblingStyleChanges(this, FinishedParsingChildren, ElementTraversal::lastChild(this), nullptr);
     if (auto styleResolver = document().styleResolverIfExists())
         styleResolver->popParentElement(this);
 }

 #ifndef NDEBUG
 void Element::formatForDebugger(char* buffer, unsigned length) const
 {
     StringBuilder result;
     String s;

     result.append(nodeName());

     s = getIdAttribute();
     if (s.length() > 0) {
         if (result.length() > 0)
             result.appendLiteral("; ");
         result.appendLiteral("id=");
         result.append(s);
     }

     s = getAttribute(classAttr);
     if (s.length() > 0) {
         if (result.length() > 0)
             result.appendLiteral("; ");
         result.appendLiteral("class=");
         result.append(s);
     }

     strncpy(buffer, result.toString().utf8().data(), length - 1);
 }
 #endif

 const Vector<RefPtr<Attr>>& Element::attrNodeList()
 {
     ASSERT(hasSyntheticAttrChildNodes());
     return *attrNodeListForElement(*this);
 }

 RefPtr<Attr> Element::setAttributeNode(Attr* attrNode, ExceptionCode& ec)
 {
     if (!attrNode) {
         ec = TYPE_MISMATCH_ERR;
         return 0;
     }

     RefPtr<Attr> oldAttrNode = attrIfExists(attrNode->qualifiedName());
     if (oldAttrNode.get() == attrNode)
         return attrNode; // This Attr is already attached to the element.

     // INUSE_ATTRIBUTE_ERR: Raised if node is an Attr that is already an attribute of another Element object.
     // The DOM user must explicitly clone Attr nodes to re-use them in other elements.
     if (attrNode->ownerElement()) {
         ec = INUSE_ATTRIBUTE_ERR;
         return 0;
     }

     synchronizeAllAttributes();
     UniqueElementData& elementData = ensureUniqueElementData();

     unsigned index = elementData.findAttributeIndexByNameForAttributeNode(attrNode, shouldIgnoreAttributeCase(*this));
     if (index != ElementData::attributeNotFound) {
         if (oldAttrNode)
             detachAttrNodeFromElementWithValue(oldAttrNode.get(), elementData.attributeAt(index).value());
         else
             oldAttrNode = Attr::create(document(), attrNode->qualifiedName(), elementData.attributeAt(index).value());
     }

     setAttributeInternal(index, attrNode->qualifiedName(), attrNode->value(), NotInSynchronizationOfLazyAttribute);

     attrNode->attachToElement(this);
     treeScope().adoptIfNeeded(attrNode);
     ensureAttrNodeListForElement(*this).append(attrNode);

     return oldAttrNode.release();
 }

 RefPtr<Attr> Element::setAttributeNodeNS(Attr* attr, ExceptionCode& ec)
 {
     return setAttributeNode(attr, ec);
 }

 RefPtr<Attr> Element::removeAttributeNode(Attr* attr, ExceptionCode& ec)
 {
     if (!attr) {
         ec = TYPE_MISMATCH_ERR;
         return 0;
     }
     if (attr->ownerElement() != this) {
         ec = NOT_FOUND_ERR;
         return 0;
     }

     ASSERT(&document() == &attr->document());

     synchronizeAttribute(attr->qualifiedName());

     unsigned index = elementData()->findAttributeIndexByNameForAttributeNode(attr);
     if (index == ElementData::attributeNotFound) {
         ec = NOT_FOUND_ERR;
         return 0;
     }

     RefPtr<Attr> attrNode = attr;
     detachAttrNodeFromElementWithValue(attr, elementData()->attributeAt(index).value());
     removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
     return attrNode.release();
 }

 bool Element::parseAttributeName(QualifiedName& out, const AtomicString& namespaceURI, const AtomicString& qualifiedName, ExceptionCode& ec)
 {
     String prefix, localName;
     if (!Document::parseQualifiedName(qualifiedName, prefix, localName, ec))
         return false;
     ASSERT(!ec);

     QualifiedName qName(prefix, localName, namespaceURI);

     if (!Document::hasValidNamespaceForAttributes(qName)) {
         ec = NAMESPACE_ERR;
         return false;
     }

     out = qName;
     return true;
 }

 void Element::setAttributeNS(const AtomicString& namespaceURI, const AtomicString& qualifiedName, const AtomicString& value, ExceptionCode& ec)
 {
     QualifiedName parsedName = anyName;
     if (!parseAttributeName(parsedName, namespaceURI, qualifiedName, ec))
         return;
     setAttribute(parsedName, value);
 }

 void Element::removeAttributeInternal(unsigned index, SynchronizationOfLazyAttribute inSynchronizationOfLazyAttribute)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(index < attributeCount());

     UniqueElementData& elementData = ensureUniqueElementData();

     QualifiedName name = elementData.attributeAt(index).name();
     AtomicString valueBeingRemoved = elementData.attributeAt(index).value();

     if (!inSynchronizationOfLazyAttribute) {
         if (!valueBeingRemoved.isNull())
             willModifyAttribute(name, valueBeingRemoved, nullAtom);
     }

     if (RefPtr<Attr> attrNode = attrIfExists(name))
         detachAttrNodeFromElementWithValue(attrNode.get(), elementData.attributeAt(index).value());

     elementData.removeAttribute(index);

     if (!inSynchronizationOfLazyAttribute)
         didRemoveAttribute(name, valueBeingRemoved);
 }

 void Element::addAttributeInternal(const QualifiedName& name, const AtomicString& value, SynchronizationOfLazyAttribute inSynchronizationOfLazyAttribute)
 {
     if (!inSynchronizationOfLazyAttribute)
         willModifyAttribute(name, nullAtom, value);
     ensureUniqueElementData().addAttribute(name, value);
     if (!inSynchronizationOfLazyAttribute)
         didAddAttribute(name, value);
 }

 bool Element::removeAttribute(const AtomicString& name)
 {
     if (!elementData())
         return false;

     AtomicString localName = shouldIgnoreAttributeCase(*this) ? name.lower() : name;
     unsigned index = elementData()->findAttributeIndexByName(localName, false);
     if (index == ElementData::attributeNotFound) {
         if (UNLIKELY(localName == styleAttr) && elementData()->styleAttributeIsDirty() && is<StyledElement>(*this))
             downcast<StyledElement>(*this).removeAllInlineStyleProperties();
         return false;
     }

     removeAttributeInternal(index, NotInSynchronizationOfLazyAttribute);
     return true;
 }

 bool Element::removeAttributeNS(const AtomicString& namespaceURI, const AtomicString& localName)
 {
     return removeAttribute(QualifiedName(nullAtom, localName, namespaceURI));
 }

 RefPtr<Attr> Element::getAttributeNode(const AtomicString& localName)
 {
     if (!elementData())
         return 0;
     synchronizeAttribute(localName);
     const Attribute* attribute = elementData()->findAttributeByName(localName, shouldIgnoreAttributeCase(*this));
     if (!attribute)
         return 0;
     return ensureAttr(attribute->name());
 }

 RefPtr<Attr> Element::getAttributeNodeNS(const AtomicString& namespaceURI, const AtomicString& localName)
 {
     if (!elementData())
         return 0;
     QualifiedName qName(nullAtom, localName, namespaceURI);
     synchronizeAttribute(qName);
     const Attribute* attribute = elementData()->findAttributeByName(qName);
     if (!attribute)
         return 0;
     return ensureAttr(attribute->name());
 }

 bool Element::hasAttribute(const AtomicString& localName) const
 {
     if (!elementData())
         return false;
     synchronizeAttribute(localName);
     return elementData()->findAttributeByName(shouldIgnoreAttributeCase(*this) ? localName.lower() : localName, false);
 }

 bool Element::hasAttributeNS(const AtomicString& namespaceURI, const AtomicString& localName) const
 {
     if (!elementData())
         return false;
     QualifiedName qName(nullAtom, localName, namespaceURI);
     synchronizeAttribute(qName);
     return elementData()->findAttributeByName(qName);
 }

 CSSStyleDeclaration *Element::style()
 {
     return 0;
 }

 void Element::focus(bool restorePreviousSelection, FocusDirection direction)
 {
     if (!inDocument())
         return;

     if (document().focusedElement() == this)
         return;

     // If the stylesheets have already been loaded we can reliably check isFocusable.
     // If not, we continue and set the focused node on the focus controller below so
     // that it can be updated soon after attach.
     if (document().haveStylesheetsLoaded()) {
         document().updateLayoutIgnorePendingStylesheets();
         if (!isFocusable())
             return;
     }

     if (!supportsFocus())
         return;

     RefPtr<Node> protect;
     if (Page* page = document().page()) {
         // Focus and change event handlers can cause us to lose our last ref.
         // If a focus event handler changes the focus to a different node it
         // does not make sense to continue and update appearence.
         protect = this;
         if (!page->focusController().setFocusedElement(this, document().frame(), direction))
             return;
     }

     // Setting the focused node above might have invalidated the layout due to scripts.
     document().updateLayoutIgnorePendingStylesheets();

     if (!isFocusable()) {
         ensureElementRareData().setNeedsFocusAppearanceUpdateSoonAfterAttach(true);
         return;
     }

     cancelFocusAppearanceUpdate();
 #if PLATFORM(IOS)
     // Focusing a form element triggers animation in UIKit to scroll to the right position.
     // Calling updateFocusAppearance() would generate an unnecessary call to ScrollView::setScrollPosition(),
     // which would jump us around during this animation. See <rdar://problem/6699741>.
     FrameView* view = document().view();
     bool isFormControl = view && is<HTMLFormControlElement>(*this);
     if (isFormControl)
         view->setProhibitsScrolling(true);
 #endif
     updateFocusAppearance(restorePreviousSelection);
 #if PLATFORM(IOS)
     if (isFormControl)
         view->setProhibitsScrolling(false);
 #endif
 }

 void Element::updateFocusAppearanceAfterAttachIfNeeded()
 {
     if (!hasRareData())
         return;
     ElementRareData* data = elementRareData();
     if (!data->needsFocusAppearanceUpdateSoonAfterAttach())
         return;
     if (isFocusable() && document().focusedElement() == this)
         document().updateFocusAppearanceSoon(false /* don't restore selection */);
     data->setNeedsFocusAppearanceUpdateSoonAfterAttach(false);
 }

 void Element::updateFocusAppearance(bool /*restorePreviousSelection*/)
 {
     if (isRootEditableElement()) {
         Frame* frame = document().frame();
         if (!frame)
             return;

         // When focusing an editable element in an iframe, don't reset the selection if it already contains a selection.
         if (this == frame->selection().selection().rootEditableElement())
             return;

         // FIXME: We should restore the previous selection if there is one.
         VisibleSelection newSelection = VisibleSelection(firstPositionInOrBeforeNode(this), DOWNSTREAM);

         if (frame->selection().shouldChangeSelection(newSelection)) {
             frame->selection().setSelection(newSelection);
             frame->selection().revealSelection();
         }
     } else if (renderer() && !renderer()->isWidget())
         renderer()->scrollRectToVisible(renderer()->anchorRect());
 }

 void Element::blur()
 {
     cancelFocusAppearanceUpdate();
     if (treeScope().focusedElement() == this) {
         if (Frame* frame = document().frame())
             frame->page()->focusController().setFocusedElement(0, frame);
         else
             document().setFocusedElement(0);
     }
 }

 void Element::dispatchFocusInEvent(const AtomicString& eventType, RefPtr<Element>&& oldFocusedElement)
 {
     ASSERT(!NoEventDispatchAssertion::isEventDispatchForbidden());
     ASSERT(eventType == eventNames().focusinEvent || eventType == eventNames().DOMFocusInEvent);
     dispatchScopedEvent(FocusEvent::create(eventType, true, false, document().defaultView(), 0, WTF::move(oldFocusedElement)));
 }

 void Element::dispatchFocusOutEvent(const AtomicString& eventType, RefPtr<Element>&& newFocusedElement)
 {
     ASSERT(!NoEventDispatchAssertion::isEventDispatchForbidden());
     ASSERT(eventType == eventNames().focusoutEvent || eventType == eventNames().DOMFocusOutEvent);
     dispatchScopedEvent(FocusEvent::create(eventType, true, false, document().defaultView(), 0, WTF::move(newFocusedElement)));
 }

 void Element::dispatchFocusEvent(RefPtr<Element>&& oldFocusedElement, FocusDirection)
 {
     if (document().page())
         document().page()->chrome().client().elementDidFocus(this);

     EventDispatcher::dispatchEvent(this, FocusEvent::create(eventNames().focusEvent, false, false, document().defaultView(), 0, WTF::move(oldFocusedElement)));
 }

 void Element::dispatchBlurEvent(RefPtr<Element>&& newFocusedElement)
 {
     if (document().page())
         document().page()->chrome().client().elementDidBlur(this);

     EventDispatcher::dispatchEvent(this, FocusEvent::create(eventNames().blurEvent, false, false, document().defaultView(), 0, WTF::move(newFocusedElement)));
 }

 void Element::mergeWithNextTextNode(Text& node, ExceptionCode& ec)
 {
     Node* next = node.nextSibling();
     if (!is<Text>(next))
         return;

     Ref<Text> textNode(node);
     Ref<Text> textNext(downcast<Text>(*next));
     textNode->appendData(textNext->data(), ec);
     if (ec)
         return;
     textNext->remove(ec);
 }

 String Element::innerHTML() const
 {
     return createMarkup(*this, ChildrenOnly);
 }

 String Element::outerHTML() const
 {
     return createMarkup(*this);
 }

 void Element::setOuterHTML(const String& html, ExceptionCode& ec)
 {
     Element* p = parentElement();
     if (!is<HTMLElement>(p)) {
         ec = NO_MODIFICATION_ALLOWED_ERR;
         return;
     }
     RefPtr<HTMLElement> parent = downcast<HTMLElement>(p);
     RefPtr<Node> prev = previousSibling();
     RefPtr<Node> next = nextSibling();

     RefPtr<DocumentFragment> fragment = createFragmentForInnerOuterHTML(html, parent.get(), AllowScriptingContent, ec);
     if (ec)
         return;

     parent->replaceChild(fragment.release(), this, ec);
     RefPtr<Node> node = next ? next->previousSibling() : nullptr;
     if (!ec && is<Text>(node.get()))
         mergeWithNextTextNode(downcast<Text>(*node), ec);
     if (!ec && is<Text>(prev.get()))
         mergeWithNextTextNode(downcast<Text>(*prev), ec);
 }


 void Element::setInnerHTML(const String& html, ExceptionCode& ec)
 {
     if (RefPtr<DocumentFragment> fragment = createFragmentForInnerOuterHTML(html, this, AllowScriptingContent, ec)) {
         ContainerNode* container = this;

 #if ENABLE(TEMPLATE_ELEMENT)
         if (is<HTMLTemplateElement>(*this))
             container = downcast<HTMLTemplateElement>(*this).content();
 #endif

         replaceChildrenWithFragment(*container, fragment.release(), ec);
     }
 }

 String Element::innerText()
 {
     // We need to update layout, since plainText uses line boxes in the render tree.
     document().updateLayoutIgnorePendingStylesheets();

     if (!renderer())
         return textContent(true);

     return plainText(rangeOfContents(*this).ptr());
 }

 String Element::outerText()
 {
     // Getting outerText is the same as getting innerText, only
     // setting is different. You would think this should get the plain
     // text for the outer range, but this is wrong, <br> for instance
     // would return different values for inner and outer text by such
     // a rule, but it doesn't in WinIE, and we want to match that.
     return innerText();
 }

 String Element::title() const
 {
     return String();
 }

 const AtomicString& Element::pseudo() const
 {
     return fastGetAttribute(pseudoAttr);
 }

 void Element::setPseudo(const AtomicString& value)
 {
     setAttributeWithoutSynchronization(pseudoAttr, value);
 }

 LayoutSize Element::minimumSizeForResizing() const
 {
     return hasRareData() ? elementRareData()->minimumSizeForResizing() : defaultMinimumSizeForResizing();
 }

 void Element::setMinimumSizeForResizing(const LayoutSize& size)
 {
     if (!hasRareData() && size == defaultMinimumSizeForResizing())
         return;
     ensureElementRareData().setMinimumSizeForResizing(size);
 }

 static PseudoElement* beforeOrAfterPseudoElement(Element* host, PseudoId pseudoElementSpecifier)
 {
     switch (pseudoElementSpecifier) {
     case BEFORE:
         return host->beforePseudoElement();
     case AFTER:
         return host->afterPseudoElement();
     default:
         return 0;
     }
 }

 RenderStyle* Element::computedStyle(PseudoId pseudoElementSpecifier)
 {
     if (PseudoElement* pseudoElement = beforeOrAfterPseudoElement(this, pseudoElementSpecifier))
         return pseudoElement->computedStyle();

     // FIXME: Find and use the renderer from the pseudo element instead of the actual element so that the 'length'
     // properties, which are only known by the renderer because it did the layout, will be correct and so that the
     // values returned for the ":selection" pseudo-element will be correct.
     if (RenderStyle* usedStyle = renderStyle()) {
         if (pseudoElementSpecifier) {
             RenderStyle* cachedPseudoStyle = usedStyle->getCachedPseudoStyle(pseudoElementSpecifier);
             return cachedPseudoStyle ? cachedPseudoStyle : usedStyle;
         }
         return usedStyle;
     }

     if (!inDocument()) {
         // FIXME: Try to do better than this. Ensure that styleForElement() works for elements that are not in the
         // document tree and figure out when to destroy the computed style for such elements.
         return nullptr;
     }

     ElementRareData& data = ensureElementRareData();
     if (!data.computedStyle())
         data.setComputedStyle(document().styleForElementIgnoringPendingStylesheets(this));
     return pseudoElementSpecifier ? data.computedStyle()->getCachedPseudoStyle(pseudoElementSpecifier) : data.computedStyle();
 }

 void Element::setStyleAffectedByEmpty()
 {
     ensureElementRareData().setStyleAffectedByEmpty(true);
 }

 void Element::setChildrenAffectedByActive()
 {
     ensureElementRareData().setChildrenAffectedByActive(true);
 }

 void Element::setChildrenAffectedByDrag()
 {
     ensureElementRareData().setChildrenAffectedByDrag(true);
 }

 void Element::setChildrenAffectedByBackwardPositionalRules()
 {
     ensureElementRareData().setChildrenAffectedByBackwardPositionalRules(true);
 }

 void Element::setChildrenAffectedByPropertyBasedBackwardPositionalRules()
 {
     ensureElementRareData().setChildrenAffectedByPropertyBasedBackwardPositionalRules(true);
 }

 void Element::setChildIndex(unsigned index)
 {
     ElementRareData& rareData = ensureElementRareData();
     if (RenderStyle* style = renderStyle())
         style->setUnique();
     rareData.setChildIndex(index);
 }

 bool Element::hasFlagsSetDuringStylingOfChildren() const
 {
     if (childrenAffectedByHover() || childrenAffectedByFirstChildRules() || childrenAffectedByLastChildRules())
         return true;

     if (!hasRareData())
         return false;
     return rareDataChildrenAffectedByActive()
         || rareDataChildrenAffectedByDrag()
         || rareDataChildrenAffectedByBackwardPositionalRules()
         || rareDataChildrenAffectedByPropertyBasedBackwardPositionalRules();
 }

 bool Element::rareDataStyleAffectedByEmpty() const
 {
     ASSERT(hasRareData());
     return elementRareData()->styleAffectedByEmpty();
 }

 bool Element::rareDataChildrenAffectedByActive() const
 {
     ASSERT(hasRareData());
     return elementRareData()->childrenAffectedByActive();
 }

 bool Element::rareDataChildrenAffectedByDrag() const
 {
     ASSERT(hasRareData());
     return elementRareData()->childrenAffectedByDrag();
 }

 bool Element::rareDataChildrenAffectedByBackwardPositionalRules() const
 {
     ASSERT(hasRareData());
     return elementRareData()->childrenAffectedByBackwardPositionalRules();
 }

 bool Element::rareDataChildrenAffectedByPropertyBasedBackwardPositionalRules() const
 {
     ASSERT(hasRareData());
     return elementRareData()->childrenAffectedByPropertyBasedBackwardPositionalRules();
 }

 unsigned Element::rareDataChildIndex() const
 {
     ASSERT(hasRareData());
     return elementRareData()->childIndex();
 }

 void Element::setRegionOversetState(RegionOversetState state)
 {
     ensureElementRareData().setRegionOversetState(state);
 }

 RegionOversetState Element::regionOversetState() const
 {
     return hasRareData() ? elementRareData()->regionOversetState() : RegionUndefined;
 }

 AtomicString Element::computeInheritedLanguage() const
 {
     if (const ElementData* elementData = this->elementData()) {
         if (const Attribute* attribute = elementData->findLanguageAttribute())
             return attribute->value();
     }

     // The language property is inherited, so we iterate over the parents to find the first language.
     const Node* currentNode = this;
     while ((currentNode = currentNode->parentNode())) {
         if (is<Element>(*currentNode)) {
             if (const ElementData* elementData = downcast<Element>(*currentNode).elementData()) {
                 if (const Attribute* attribute = elementData->findLanguageAttribute())
                     return attribute->value();
             }
         } else if (is<Document>(*currentNode)) {
             // checking the MIME content-language
             return downcast<Document>(*currentNode).contentLanguage();
         }
     }

     return nullAtom;
 }

 Locale& Element::locale() const
 {
     return document().getCachedLocale(computeInheritedLanguage());
 }

 void Element::cancelFocusAppearanceUpdate()
 {
     if (hasRareData())
         elementRareData()->setNeedsFocusAppearanceUpdateSoonAfterAttach(false);
     if (document().focusedElement() == this)
         document().cancelFocusAppearanceUpdate();
 }

 void Element::normalizeAttributes()
 {
     if (!hasAttributes())
         return;
     for (const Attribute& attribute : attributesIterator()) {
         if (RefPtr<Attr> attr = attrIfExists(attribute.name()))
             attr->normalize();
     }
 }

 PseudoElement* Element::beforePseudoElement() const
 {
     return hasRareData() ? elementRareData()->beforePseudoElement() : 0;
 }

 PseudoElement* Element::afterPseudoElement() const
 {
     return hasRareData() ? elementRareData()->afterPseudoElement() : 0;
 }

 void Element::setBeforePseudoElement(Ref<PseudoElement>&& element)
 {
     ensureElementRareData().setBeforePseudoElement(WTF::move(element));
 }

 void Element::setAfterPseudoElement(Ref<PseudoElement>&& element)
 {
     ensureElementRareData().setAfterPseudoElement(WTF::move(element));
 }

 static void disconnectPseudoElement(PseudoElement* pseudoElement)
 {
     if (!pseudoElement)
         return;
     if (pseudoElement->renderer())
         Style::detachRenderTree(*pseudoElement);
     ASSERT(pseudoElement->hostElement());
     pseudoElement->clearHostElement();
 }

 void Element::clearBeforePseudoElement()
 {
     if (!hasRareData())
         return;
     disconnectPseudoElement(elementRareData()->beforePseudoElement());
     elementRareData()->setBeforePseudoElement(nullptr);
 }

 void Element::clearAfterPseudoElement()
 {
     if (!hasRareData())
         return;
     disconnectPseudoElement(elementRareData()->afterPseudoElement());
     elementRareData()->setAfterPseudoElement(nullptr);
 }

 // ElementTraversal API
 Element* Element::firstElementChild() const
 {
     return ElementTraversal::firstChild(this);
 }

 Element* Element::lastElementChild() const
 {
     return ElementTraversal::lastChild(this);
 }

 Element* Element::previousElementSibling() const
 {
     return ElementTraversal::previousSibling(this);
 }

 Element* Element::nextElementSibling() const
 {
     return ElementTraversal::nextSibling(this);
 }

 unsigned Element::childElementCount() const
 {
     unsigned count = 0;
     Node* n = firstChild();
     while (n) {
         count += n->isElementNode();
         n = n->nextSibling();
     }
     return count;
 }

 bool Element::matchesReadWritePseudoClass() const
 {
     return false;
 }

 bool Element::matches(const String& selector, ExceptionCode& ec)
 {
     SelectorQuery* selectorQuery = document().selectorQueryForString(selector, ec);
     return selectorQuery && selectorQuery->matches(*this);
 }

 Element* Element::closest(const String& selector, ExceptionCode& ec)
 {
     SelectorQuery* selectorQuery = document().selectorQueryForString(selector, ec);
     if (selectorQuery)
         return selectorQuery->closest(*this);
     return nullptr;
 }

 bool Element::shouldAppearIndeterminate() const
 {
     return false;
 }

 bool Element::mayCauseRepaintInsideViewport(const IntRect* visibleRect) const
 {
     return renderer() && renderer()->mayCauseRepaintInsideViewport(visibleRect);
 }

 DOMTokenList& Element::classList()
 {
     ElementRareData& data = ensureElementRareData();
     if (!data.classList())
         data.setClassList(std::make_unique<ClassList>(*this));
     return *data.classList();
 }

 DatasetDOMStringMap& Element::dataset()
 {
     ElementRareData& data = ensureElementRareData();
     if (!data.dataset())
         data.setDataset(std::make_unique<DatasetDOMStringMap>(*this));
     return *data.dataset();
 }

 URL Element::getURLAttribute(const QualifiedName& name) const
 {
 #if !ASSERT_DISABLED
     if (elementData()) {
         if (const Attribute* attribute = findAttributeByName(name))
             ASSERT(isURLAttribute(*attribute));
     }
 #endif
     return document().completeURL(stripLeadingAndTrailingHTMLSpaces(getAttribute(name)));
 }

 URL Element::getNonEmptyURLAttribute(const QualifiedName& name) const
 {
 #if !ASSERT_DISABLED
     if (elementData()) {
         if (const Attribute* attribute = findAttributeByName(name))
             ASSERT(isURLAttribute(*attribute));
     }
 #endif
     String value = stripLeadingAndTrailingHTMLSpaces(getAttribute(name));
     if (value.isEmpty())
         return URL();
     return document().completeURL(value);
 }

 int Element::getIntegralAttribute(const QualifiedName& attributeName) const
 {
     return getAttribute(attributeName).string().toInt();
 }

 void Element::setIntegralAttribute(const QualifiedName& attributeName, int value)
 {
     setAttribute(attributeName, AtomicString::number(value));
 }

 unsigned Element::getUnsignedIntegralAttribute(const QualifiedName& attributeName) const
 {
     return getAttribute(attributeName).string().toUInt();
 }

 void Element::setUnsignedIntegralAttribute(const QualifiedName& attributeName, unsigned value)
 {
     setAttribute(attributeName, AtomicString::number(value));
 }

 #if ENABLE(INDIE_UI)
 void Element::setUIActions(const AtomicString& actions)
 {
     setAttribute(uiactionsAttr, actions);
 }

 const AtomicString& Element::UIActions() const
 {
     return getAttribute(uiactionsAttr);
 }
 #endif

 bool Element::childShouldCreateRenderer(const Node& child) const
 {
     // Only create renderers for SVG elements whose parents are SVG elements, or for proper <svg xmlns="svgNS"> subdocuments.
     if (child.isSVGElement()) {
         ASSERT(!isSVGElement());
         const SVGElement& childElement = downcast<SVGElement>(child);
         return is<SVGSVGElement>(childElement) && childElement.isValid();
     }
     return true;
 }

 #if ENABLE(FULLSCREEN_API)
 void Element::webkitRequestFullscreen()
 {
     document().requestFullScreenForElement(this, ALLOW_KEYBOARD_INPUT, Document::EnforceIFrameAllowFullScreenRequirement);
 }

 void Element::webkitRequestFullScreen(unsigned short flags)
 {
     document().requestFullScreenForElement(this, (flags | LEGACY_MOZILLA_REQUEST), Document::EnforceIFrameAllowFullScreenRequirement);
 }

 bool Element::containsFullScreenElement() const
 {
     return hasRareData() && elementRareData()->containsFullScreenElement();
 }

 void Element::setContainsFullScreenElement(bool flag)
 {
     ensureElementRareData().setContainsFullScreenElement(flag);
     setNeedsStyleRecalc(SyntheticStyleChange);
 }

 static Element* parentCrossingFrameBoundaries(Element* element)
 {
     ASSERT(element);
     return element->parentElement() ? element->parentElement() : element->document().ownerElement();
 }

 void Element::setContainsFullScreenElementOnAncestorsCrossingFrameBoundaries(bool flag)
 {
     Element* element = this;
     while ((element = parentCrossingFrameBoundaries(element)))
         element->setContainsFullScreenElement(flag);
 }
 #endif

 #if ENABLE(POINTER_LOCK)
 void Element::requestPointerLock()
 {
     if (document().page())
         document().page()->pointerLockController().requestPointerLock(this);
 }
 #endif

 SpellcheckAttributeState Element::spellcheckAttributeState() const
 {
     const AtomicString& value = fastGetAttribute(HTMLNames::spellcheckAttr);
     if (value == nullAtom)
         return SpellcheckAttributeDefault;
     if (equalIgnoringCase(value, "true") || equalIgnoringCase(value, ""))
         return SpellcheckAttributeTrue;
     if (equalIgnoringCase(value, "false"))
         return SpellcheckAttributeFalse;

     return SpellcheckAttributeDefault;
 }

 bool Element::isSpellCheckingEnabled() const
 {
     for (const Element* element = this; element; element = element->parentOrShadowHostElement()) {
         switch (element->spellcheckAttributeState()) {
         case SpellcheckAttributeTrue:
             return true;
         case SpellcheckAttributeFalse:
             return false;
         case SpellcheckAttributeDefault:
             break;
         }
     }

     return true;
 }

 RenderNamedFlowFragment* Element::renderNamedFlowFragment() const
 {
     if (renderer() && renderer()->isRenderNamedFlowFragmentContainer())
         return downcast<RenderBlockFlow>(*renderer()).renderNamedFlowFragment();

     return nullptr;
 }

 #if ENABLE(CSS_REGIONS)

 bool Element::shouldMoveToFlowThread(const RenderStyle& styleToUse) const
 {
 #if ENABLE(FULLSCREEN_API)
     if (document().webkitIsFullScreen() && document().webkitCurrentFullScreenElement() == this)
         return false;
 #endif

     if (isInShadowTree())
         return false;

     if (!styleToUse.hasFlowInto())
         return false;

     return true;
 }

 const AtomicString& Element::webkitRegionOverset() const
 {
     document().updateLayoutIgnorePendingStylesheets();

     DEPRECATED_DEFINE_STATIC_LOCAL(AtomicString, undefinedState, ("undefined", AtomicString::ConstructFromLiteral));
     if (!document().cssRegionsEnabled() || !renderNamedFlowFragment())
         return undefinedState;

     switch (regionOversetState()) {
     case RegionFit: {
         DEPRECATED_DEFINE_STATIC_LOCAL(AtomicString, fitState, ("fit", AtomicString::ConstructFromLiteral));
         return fitState;
     }
     case RegionEmpty: {
         DEPRECATED_DEFINE_STATIC_LOCAL(AtomicString, emptyState, ("empty", AtomicString::ConstructFromLiteral));
         return emptyState;
     }
     case RegionOverset: {
         DEPRECATED_DEFINE_STATIC_LOCAL(AtomicString, overflowState, ("overset", AtomicString::ConstructFromLiteral));
         return overflowState;
     }
     case RegionUndefined:
         return undefinedState;
     }

     ASSERT_NOT_REACHED();
     return undefinedState;
 }

 Vector<RefPtr<Range>> Element::webkitGetRegionFlowRanges() const
 {
     Vector<RefPtr<Range>> rangeObjects;
     if (!document().cssRegionsEnabled())
         return rangeObjects;

     document().updateLayoutIgnorePendingStylesheets();
     if (renderer() && renderer()->isRenderNamedFlowFragmentContainer()) {
         RenderNamedFlowFragment& namedFlowFragment = *downcast<RenderBlockFlow>(*renderer()).renderNamedFlowFragment();
         if (namedFlowFragment.isValid())
             namedFlowFragment.getRanges(rangeObjects);
     }

     return rangeObjects;
 }

 #endif

 #ifndef NDEBUG
 bool Element::fastAttributeLookupAllowed(const QualifiedName& name) const
 {
     if (name == HTMLNames::styleAttr)
         return false;

     if (isSVGElement())
         return !downcast<SVGElement>(*this).isAnimatableAttribute(name);

     return true;
 }
 #endif

 #ifdef DUMP_NODE_STATISTICS
 bool Element::hasNamedNodeMap() const
 {
     return hasRareData() && elementRareData()->attributeMap();
 }
 #endif

 inline void Element::updateName(const AtomicString& oldName, const AtomicString& newName)
 {
     if (!isInTreeScope())
         return;

     if (oldName == newName)
         return;

     updateNameForTreeScope(treeScope(), oldName, newName);

     if (!inDocument())
         return;
     if (!is<HTMLDocument>(document()))
         return;
     updateNameForDocument(downcast<HTMLDocument>(document()), oldName, newName);
 }

 void Element::updateNameForTreeScope(TreeScope& scope, const AtomicString& oldName, const AtomicString& newName)
 {
     ASSERT(oldName != newName);

     if (!oldName.isEmpty())
         scope.removeElementByName(*oldName.impl(), *this);
     if (!newName.isEmpty())
         scope.addElementByName(*newName.impl(), *this);
 }

 void Element::updateNameForDocument(HTMLDocument& document, const AtomicString& oldName, const AtomicString& newName)
 {
     ASSERT(oldName != newName);

     if (WindowNameCollection::elementMatchesIfNameAttributeMatch(*this)) {
         const AtomicString& id = WindowNameCollection::elementMatchesIfIdAttributeMatch(*this) ? getIdAttribute() : nullAtom;
         if (!oldName.isEmpty() && oldName != id)
             document.removeWindowNamedItem(*oldName.impl(), *this);
         if (!newName.isEmpty() && newName != id)
             document.addWindowNamedItem(*newName.impl(), *this);
     }

     if (DocumentNameCollection::elementMatchesIfNameAttributeMatch(*this)) {
         const AtomicString& id = DocumentNameCollection::elementMatchesIfIdAttributeMatch(*this) ? getIdAttribute() : nullAtom;
         if (!oldName.isEmpty() && oldName != id)
             document.removeDocumentNamedItem(*oldName.impl(), *this);
         if (!newName.isEmpty() && newName != id)
             document.addDocumentNamedItem(*newName.impl(), *this);
     }
 }

 inline void Element::updateId(const AtomicString& oldId, const AtomicString& newId)
 {
     if (!isInTreeScope())
         return;

     if (oldId == newId)
         return;

     updateIdForTreeScope(treeScope(), oldId, newId);

     if (!inDocument())
         return;
     if (!is<HTMLDocument>(document()))
         return;
     updateIdForDocument(downcast<HTMLDocument>(document()), oldId, newId, UpdateHTMLDocumentNamedItemMapsOnlyIfDiffersFromNameAttribute);
 }

 void Element::updateIdForTreeScope(TreeScope& scope, const AtomicString& oldId, const AtomicString& newId)
 {
     ASSERT(isInTreeScope());
     ASSERT(oldId != newId);

     if (!oldId.isEmpty())
         scope.removeElementById(*oldId.impl(), *this);
     if (!newId.isEmpty())
         scope.addElementById(*newId.impl(), *this);
 }

 void Element::updateIdForDocument(HTMLDocument& document, const AtomicString& oldId, const AtomicString& newId, HTMLDocumentNamedItemMapsUpdatingCondition condition)
 {
     ASSERT(inDocument());
     ASSERT(oldId != newId);

     if (WindowNameCollection::elementMatchesIfIdAttributeMatch(*this)) {
         const AtomicString& name = condition == UpdateHTMLDocumentNamedItemMapsOnlyIfDiffersFromNameAttribute && WindowNameCollection::elementMatchesIfNameAttributeMatch(*this) ? getNameAttribute() : nullAtom;
         if (!oldId.isEmpty() && oldId != name)
             document.removeWindowNamedItem(*oldId.impl(), *this);
         if (!newId.isEmpty() && newId != name)
             document.addWindowNamedItem(*newId.impl(), *this);
     }

     if (DocumentNameCollection::elementMatchesIfIdAttributeMatch(*this)) {
         const AtomicString& name = condition == UpdateHTMLDocumentNamedItemMapsOnlyIfDiffersFromNameAttribute && DocumentNameCollection::elementMatchesIfNameAttributeMatch(*this) ? getNameAttribute() : nullAtom;
         if (!oldId.isEmpty() && oldId != name)
             document.removeDocumentNamedItem(*oldId.impl(), *this);
         if (!newId.isEmpty() && newId != name)
             document.addDocumentNamedItem(*newId.impl(), *this);
     }
 }

 void Element::updateLabel(TreeScope& scope, const AtomicString& oldForAttributeValue, const AtomicString& newForAttributeValue)
 {
     ASSERT(hasTagName(labelTag));

     if (!inDocument())
         return;

     if (oldForAttributeValue == newForAttributeValue)
         return;

     if (!oldForAttributeValue.isEmpty())
         scope.removeLabel(*oldForAttributeValue.impl(), downcast<HTMLLabelElement>(*this));
     if (!newForAttributeValue.isEmpty())
         scope.addLabel(*newForAttributeValue.impl(), downcast<HTMLLabelElement>(*this));
 }

 void Element::willModifyAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue)
 {
     if (name == HTMLNames::idAttr)
         updateId(oldValue, newValue);
     else if (name == HTMLNames::nameAttr)
         updateName(oldValue, newValue);
     else if (name == HTMLNames::forAttr && hasTagName(labelTag)) {
         if (treeScope().shouldCacheLabelsByForAttribute())
             updateLabel(treeScope(), oldValue, newValue);
     }

     if (oldValue != newValue) {
         auto styleResolver = document().styleResolverIfExists();
         if (styleResolver && styleResolver->hasSelectorForAttribute(*this, name.localName()))
             setNeedsStyleRecalc();
     }

     if (std::unique_ptr<MutationObserverInterestGroup> recipients = MutationObserverInterestGroup::createForAttributesMutation(*this, name))
         recipients->enqueueMutationRecord(MutationRecord::createAttributes(*this, name, oldValue));

     InspectorInstrumentation::willModifyDOMAttr(document(), *this, oldValue, newValue);
 }

 void Element::didAddAttribute(const QualifiedName& name, const AtomicString& value)
 {
     attributeChanged(name, nullAtom, value);
     InspectorInstrumentation::didModifyDOMAttr(document(), *this, name.localName(), value);
     dispatchSubtreeModifiedEvent();
 }

 void Element::didModifyAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue)
 {
     attributeChanged(name, oldValue, newValue);
     InspectorInstrumentation::didModifyDOMAttr(document(), *this, name.localName(), newValue);
     // Do not dispatch a DOMSubtreeModified event here; see bug 81141.
 }

 void Element::didRemoveAttribute(const QualifiedName& name, const AtomicString& oldValue)
 {
     attributeChanged(name, oldValue, nullAtom);
     InspectorInstrumentation::didRemoveDOMAttr(document(), *this, name.localName());
     dispatchSubtreeModifiedEvent();
 }

 RefPtr<HTMLCollection> Element::ensureCachedHTMLCollection(CollectionType type)
 {
     if (HTMLCollection* collection = cachedHTMLCollection(type))
         return collection;

     if (type == TableRows) {
         return ensureRareData().ensureNodeLists().addCachedCollection<HTMLTableRowsCollection>(downcast<HTMLTableElement>(*this), type);
     } else if (type == SelectOptions) {
         return ensureRareData().ensureNodeLists().addCachedCollection<HTMLOptionsCollection>(downcast<HTMLSelectElement>(*this), type);
     } else if (type == FormControls) {
         ASSERT(hasTagName(formTag) || hasTagName(fieldsetTag));
         return ensureRareData().ensureNodeLists().addCachedCollection<HTMLFormControlsCollection>(*this, type);
     }
     return ensureRareData().ensureNodeLists().addCachedCollection<HTMLCollection>(*this, type);
 }

 HTMLCollection* Element::cachedHTMLCollection(CollectionType type)
 {
     return hasRareData() && rareData()->nodeLists() ? rareData()->nodeLists()->cachedCollection<HTMLCollection>(type) : 0;
 }

 IntSize Element::savedLayerScrollOffset() const
 {
     return hasRareData() ? elementRareData()->savedLayerScrollOffset() : IntSize();
 }

 void Element::setSavedLayerScrollOffset(const IntSize& size)
 {
     if (size.isZero() && !hasRareData())
         return;
     ensureElementRareData().setSavedLayerScrollOffset(size);
 }

 RefPtr<Attr> Element::attrIfExists(const QualifiedName& name)
 {
     if (auto* attrNodeList = attrNodeListForElement(*this))
         return findAttrNodeInList(*attrNodeList, name);
     return nullptr;
 }

 RefPtr<Attr> Element::ensureAttr(const QualifiedName& name)
 {
     auto& attrNodeList = ensureAttrNodeListForElement(*this);
     RefPtr<Attr> attrNode = findAttrNodeInList(attrNodeList, name);
     if (!attrNode) {
         attrNode = Attr::create(this, name);
         treeScope().adoptIfNeeded(attrNode.get());
         attrNodeList.append(attrNode);
     }
     return attrNode.release();
 }

 void Element::detachAttrNodeFromElementWithValue(Attr* attrNode, const AtomicString& value)
 {
     ASSERT(hasSyntheticAttrChildNodes());
     attrNode->detachFromElementWithValue(value);

     auto* attrNodeList = attrNodeListForElement(*this);
     for (unsigned i = 0; i < attrNodeList->size(); ++i) {
         if (attrNodeList->at(i)->qualifiedName() == attrNode->qualifiedName()) {
             attrNodeList->remove(i);
             if (attrNodeList->isEmpty())
                 removeAttrNodeListForElement(*this);
             return;
         }
     }
     ASSERT_NOT_REACHED();
 }

 void Element::detachAllAttrNodesFromElement()
 {
     auto* attrNodeList = attrNodeListForElement(*this);
     ASSERT(attrNodeList);

     for (const Attribute& attribute : attributesIterator()) {
         if (RefPtr<Attr> attrNode = findAttrNodeInList(*attrNodeList, attribute.name()))
             attrNode->detachFromElementWithValue(attribute.value());
     }

     removeAttrNodeListForElement(*this);
 }

 void Element::resetComputedStyle()
 {
     if (!hasRareData() || !elementRareData()->computedStyle())
         return;

     auto reset = [](Element& element) {
         if (!element.hasRareData() || !element.elementRareData()->computedStyle())
             return;
         if (element.hasCustomStyleResolveCallbacks())
             element.willResetComputedStyle();
         element.elementRareData()->resetComputedStyle();
     };
     reset(*this);
     for (auto& child : descendantsOfType<Element>(*this))
         reset(child);
 }

 void Element::clearStyleDerivedDataBeforeDetachingRenderer()
 {
     unregisterNamedFlowContentElement();
     cancelFocusAppearanceUpdate();
     clearBeforePseudoElement();
     clearAfterPseudoElement();
     if (!hasRareData())
         return;
     ElementRareData* data = elementRareData();
     data->resetComputedStyle();
     data->resetDynamicRestyleObservations();
 }

 void Element::clearHoverAndActiveStatusBeforeDetachingRenderer()
 {
     if (!isUserActionElement())
         return;
     if (hovered())
         document().hoveredElementDidDetach(this);
     if (inActiveChain())
         document().elementInActiveChainDidDetach(this);
     document().userActionElements().didDetach(this);
 }

 bool Element::willRecalcStyle(Style::Change)
 {
     ASSERT(hasCustomStyleResolveCallbacks());
     return true;
 }

 void Element::didRecalcStyle(Style::Change)
 {
     ASSERT(hasCustomStyleResolveCallbacks());
 }

 void Element::willResetComputedStyle()
 {
     ASSERT(hasCustomStyleResolveCallbacks());
 }

 void Element::willAttachRenderers()
 {
     ASSERT(hasCustomStyleResolveCallbacks());
 }

 void Element::didAttachRenderers()
 {
     ASSERT(hasCustomStyleResolveCallbacks());
 }

 void Element::willDetachRenderers()
 {
     ASSERT(hasCustomStyleResolveCallbacks());
 }

 void Element::didDetachRenderers()
 {
     ASSERT(hasCustomStyleResolveCallbacks());
 }

 RefPtr<RenderStyle> Element::customStyleForRenderer(RenderStyle&)
 {
     ASSERT(hasCustomStyleResolveCallbacks());
     return nullptr;
 }

 void Element::cloneAttributesFromElement(const Element& other)
 {
     if (hasSyntheticAttrChildNodes())
         detachAllAttrNodesFromElement();

     other.synchronizeAllAttributes();
     if (!other.m_elementData) {
         m_elementData.clear();
         return;
     }

     // We can't update window and document's named item maps since the presence of image and object elements depend on other attributes and children.
     // Fortunately, those named item maps are only updated when this element is in the document, which should never be the case.
     ASSERT(!inDocument());

     const AtomicString& oldID = getIdAttribute();
     const AtomicString& newID = other.getIdAttribute();

     if (!oldID.isNull() || !newID.isNull())
         updateId(oldID, newID);

     const AtomicString& oldName = getNameAttribute();
     const AtomicString& newName = other.getNameAttribute();

     if (!oldName.isNull() || !newName.isNull())
         updateName(oldName, newName);

     // If 'other' has a mutable ElementData, convert it to an immutable one so we can share it between both elements.
     // We can only do this if there is no CSSOM wrapper for other's inline style, and there are no presentation attributes.
     if (is<UniqueElementData>(*other.m_elementData)
         && !other.m_elementData->presentationAttributeStyle()
         && (!other.m_elementData->inlineStyle() || !other.m_elementData->inlineStyle()->hasCSSOMWrapper()))
         const_cast<Element&>(other).m_elementData = downcast<UniqueElementData>(*other.m_elementData).makeShareableCopy();

     if (!other.m_elementData->isUnique())
         m_elementData = other.m_elementData;
     else
         m_elementData = other.m_elementData->makeUniqueCopy();

     for (const Attribute& attribute : attributesIterator())
         attributeChanged(attribute.name(), nullAtom, attribute.value(), ModifiedByCloning);
 }

 void Element::cloneDataFromElement(const Element& other)
 {
     cloneAttributesFromElement(other);
     copyNonAttributePropertiesFromElement(other);
 }

 void Element::createUniqueElementData()
 {
     if (!m_elementData)
         m_elementData = UniqueElementData::create();
     else
         m_elementData = downcast<ShareableElementData>(*m_elementData).makeUniqueCopy();
 }

 bool Element::hasPendingResources() const
 {
     return hasRareData() && elementRareData()->hasPendingResources();
 }

 void Element::setHasPendingResources()
 {
     ensureElementRareData().setHasPendingResources(true);
 }

 void Element::clearHasPendingResources()
 {
     ensureElementRareData().setHasPendingResources(false);
 }

 bool Element::canContainRangeEndPoint() const
 {
     return !equalIgnoringCase(fastGetAttribute(roleAttr), "img");
 }

 String Element::completeURLsInAttributeValue(const URL& base, const Attribute& attribute) const
 {
     return URL(base, attribute.value()).string();
 }

 } // namespace WebCore