Repro scrolling crash with scrollbars that use setPresentationValue on the 
scrolling thread
https://bugs.webkit.org/show_bug.cgi?id=123549
-and corresponding-
<rdar://problem/15246606>

Reviewed by Brady Eidson.

Here's another speculative fix. If a scrollbar was removed, we would not properly 
inform the scrolling thread. Instead of checking supportsUpdateOnSecondaryThread() 
before calling setScrollbarPaintersFromScrollbars(), check it from within 
setScrollbarPaintersFromScrollbars(), and this will allow the ScrollbarPainter to 
be properly updated.

* page/scrolling/mac/ScrollingCoordinatorMac.mm:
(WebCore::ScrollingCoordinatorMac::frameViewLayoutUpdated):
* page/scrolling/mac/ScrollingStateScrollingNodeMac.mm:
(WebCore::ScrollingStateScrollingNode::setScrollbarPaintersFromScrollbars):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@158391 268f45cc-cd09-0410-ab3c-d52691b4dbfc
3 files changed