Some overlay scrollbar API calls in ScrollAnimatorMac can lead to an assertion in RenderBox::mapAbsoluteToLocalPoint
https://bugs.webkit.org/show_bug.cgi?id=74111

Patch by Ion Rosca <rosca@adobe.com> on 2012-06-08
Reviewed by Simon Fraser.

.:

* ManualTests/scrollbar-crash-on-hide-scrolled-area.html: Added.

Source/WebCore:

Added zero-delay timer for AppKit scroll notification that can be called during layout.
Manual test: ManualTests/scrollbar-crash-on-hide-scrolled-area.html
This assertion does not fire when running layout tests. It can be easly reproduced using a debug build by loading the manual test page.

* platform/mac/ScrollAnimatorMac.h:
(ScrollAnimatorMac):
* platform/mac/ScrollAnimatorMac.mm:
(WebCore::ScrollAnimatorMac::ScrollAnimatorMac):
(WebCore::ScrollAnimatorMac::notifyContentAreaScrolled):
(WebCore::ScrollAnimatorMac::sendContentAreaScrolledSoon):
(WebCore):
(WebCore::ScrollAnimatorMac::sendContentAreaScrolledTimerFired):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@119834 268f45cc-cd09-0410-ab3c-d52691b4dbfc