NodeRendererFactory::createRenderer calls setAnimatableStyle on the new renderer before it is attached to its parent. Because of that some RenderObjects will be tricked into thinking that the element is not part of the RenderFlowThread and for example create a composited layer when it is not supported.
Created attachment 175292 [details] Patch V1
Comment on attachment 175292 [details] Patch V1 r=me
Comment on attachment 175292 [details] Patch V1 Rejecting attachment 175292 [details] from commit-queue. Failed to run "['/mnt/git/webkit-commit-queue/Tools/Scripts/webkit-patch', '--status-host=queues.webkit.org', '-..." exit_code: 2 Last 500 characters of output: ml patching file LayoutTests/fast/repaint/region-painting-composited-element.html patching file Source/WebCore/ChangeLog Hunk #1 succeeded at 1 with fuzz 3. patching file Source/WebCore/dom/NodeRenderingContext.cpp Hunk #1 FAILED at 209. 1 out of 1 hunk FAILED -- saving rejects to file Source/WebCore/dom/NodeRenderingContext.cpp.rej Failed to run "[u'/mnt/git/webkit-commit-queue/Tools/Scripts/svn-apply', u'--force', u'--reviewer', u'David Hyatt']" exit_code: 1 cwd: /mnt/git/webkit-commit-queue Full output: http://queues.webkit.org/results/15028127
Landed manually in http://trac.webkit.org/changeset/136037.