https://bugs.webkit.org/show_bug.cgi?id=93879

Patch by Raul Hudea <rhudea@adobe.com> on 2012-08-22
Reviewed by Abhishek Arya.

Source/WebCore:

By adding the lifetime state to the RenderNamedFlowThread (r122556), it become possible for the a RenderRegion object to delete its sibling,
the RenderNamedFlowThread. This is unexpected in the rendering world and cause problems in RenderBlock::removeChild where we retain previous
and next sibling pointers.
So, all the RenderNamedFlowThread are created under a RenderFlowThreadContainer object insted of the RenderView. The new object is created only
when the first named flow is created.

Test: fast/regions/remove-flow-thread-crash.html

* CMakeLists.txt:
* GNUmakefile.list.am:
* Target.pri:
* WebCore.gypi:
* WebCore.vcproj/WebCore.vcproj:
* WebCore.xcodeproj/project.pbxproj:
* rendering/FlowThreadController.cpp:
(WebCore::FlowThreadController::FlowThreadController): Added initialization for the new RenderFlowThreadContainer member
(WebCore::FlowThreadController::ensureRenderFlowThreadWithName): Added the creation of the RenderFlowThreadContainer object and use it as a parent for all RenderNamedFlowThreads
(WebCore::FlowThreadController::styleDidChange): Inform all the RenderNamedFlowThreads that the style changed in regions (initially this code was in RenderView, but now all RenderNamedFlowThreads are children of RenderFlowThreadContainer)
(WebCore):
* rendering/FlowThreadController.h:
(WebCore):
(FlowThreadController):
* rendering/RenderFlowThreadContainer.cpp: Added.
(WebCore):
(WebCore::RenderFlowThreadContainer::RenderFlowThreadContainer):
(WebCore::RenderFlowThreadContainer::layout):
* rendering/RenderFlowThreadContainer.h: Added.
* rendering/RenderObject.cpp:
(WebCore::RenderObject::markContainingBlocksForLayout): Skip to RenderView if the current object is an RenderFlowThreadContainer.
* rendering/RenderObject.h:
(WebCore::RenderObject::isRenderFlowThreadContainer):
* rendering/RenderView.cpp:
(WebCore::RenderView::styleDidChange): Moved the code associated to RenderNamedFlowThreads to FlowThreadController:styleDidChange and call it instead.

LayoutTests:

Test the region-flow_thread sibling case

* fast/regions/remove-flow-thread-crash-expected.txt: Added.
* fast/regions/remove-flow-thread-crash.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@126304 268f45cc-cd09-0410-ab3c-d52691b4dbfc