[CSS Regions] Repaint issues when changing innerHTML of content

[CSS Regions] Repaint issues when changing innerHTML of content
https://bugs.webkit.org/show_bug.cgi?id=78787

Patch by Raul Hudea <rhudea@adobe.com> on 2012-02-16
Reviewed by David Hyatt.

Source/WebCore:

The calculation of the clipping rectangle is based on the repaint rectangle,
so it needs to be clipped to the current region, because it might spread over multiple ones.

Test: fast/repaint/region-painting-invalidation.html

* rendering/RenderFlowThread.cpp:
(WebCore::RenderFlowThread::repaintRectangleInRegions):

LayoutTests:

* fast/repaint/region-painting-invalidation.html: Added.
* platform/chromium/test_expectations.txt: Needs baseline
* platform/mac/fast/repaint/region-painting-invalidation-expected.png: Added.
* platform/mac/fast/repaint/region-painting-invalidation-expected.txt: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107959 268f45cc-cd09-0410-ab3c-d52691b4dbfc