a background layer, -webkit-background-blend-mode doesn't work.
The problem consists in the blendMode parameter not being set
for these specific drawing paths.

https://bugs.webkit.org/show_bug.cgi?id=126888
Patch by Mihai Tica <mitica@adobe.com> on 2014-01-21
Reviewed by Dirk Schulze.

Test: css3/compositing/background-blend-mode-tiled-layers.html

* platform/graphics/CrossfadeGeneratedImage.cpp:
(WebCore::CrossfadeGeneratedImage::drawPattern): Add the blendMode parameter and pass it to ImageBuffer::drawPattern.
* platform/graphics/GradientImage.cpp:
(WebCore::GradientImage::drawPattern): Add the blendMode parameter and pass it to ImageBuffer::drawPattern.
* platform/graphics/ImageBuffer.h: Add a BlendMode parameter to the drawPattern method.
* platform/graphics/cairo/ImageBufferCairo.cpp:
(WebCore::ImageBuffer::drawPattern): Add the default BlendMode parameter to the method declaration.
* platform/graphics/cg/ImageBufferCG.cpp:
(WebCore::ImageBuffer::drawPattern): Add and use the blendMode parameter for all the code paths.
* platform/graphics/wince/ImageBufferWinCE.cpp:
(WebCore::BufferedImage::drawPattern): Add the default BlendMode parameter to the method declaration.

LayoutTests: If you set a tiled cross-faded-image or a tiled gradient as
a background layer, -webkit-background-blend-mode doesn't work.
https://bugs.webkit.org/show_bug.cgi?id=126888

Patch by Mihai Tica <mitica@adobe.com> on 2014-01-21
Reviewed by Dirk Schulze.

* css3/compositing/background-blend-mode-tiled-layers-expected.html: Added.
* css3/compositing/background-blend-mode-tiled-layers.html: Added.
* platform/efl/TestExpectations: Skip test for efl, blendModes are not implemented.
* platform/mac/TestExpectations: Mark added test as ImageOnlyFailure due to slight differences between the actual result and the blending formula.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162442 268f45cc-cd09-0410-ab3c-d52691b4dbfc