[Texmap] In certain situations nested blending with overflow:hidden displays clipped results
https://bugs.webkit.org/show_bug.cgi?id=114290

Patch by Noam Rosenthal <noam@webkit.org> on 2013-04-10
Reviewed by Allan Sandfeld Jensen.

Source/WebCore:

Always apply the clip when binding a surface, even if it hasn't changed.
Otherwise when binding a nested surface and rebinding its container surface,
the clip wouldn't apply.

Test: compositing/overlap-blending/nested-overlap-overflow.html

* platform/graphics/texmap/TextureMapperGL.cpp:
(WebCore::BitmapTextureGL::bind):

LayoutTests:

Added a ref-test that exposes an issue with TextureMapper overlap blending when composited.
This ref-test does not show correct results on Mac, skipped in TestExpectations and created a bug.

* compositing/overlap-blending/nested-overlap-overflow-expected.html: Added.
* compositing/overlap-blending/nested-overlap-overflow.html: Added.
* platform/mac/TestExpectations: Skipped new tests and created bug.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148115 268f45cc-cd09-0410-ab3c-d52691b4dbfc