https://bugs.webkit.org/show_bug.cgi?id=100623

Patch by Huang Dongsung <luxtella@company100.net> on 2012-10-29
Reviewed by Noam Rosenthal.

Currently, GraphicsLayerAnimation chooses a timing function in the wrong
way. Other GraphicsLayers choose a timing function in the similar way to
GraphicsLayerCA::timingFunctionForAnimationValue(). The way consists of
the following steps.
1. Try to query the timing function of the current keyframe animation value.
2. If the timing function of #1 is null, try to query the timing function of Animation.
3. If the timing function of #2 is null, return CubicBezierTimingFunction::defaultTimingFunction().

This patch makes GraphicsLayerAnimation choose a timing function in the same way
to other implementations.

Covered by existing animations tests.

* platform/graphics/GraphicsLayerAnimation.cpp:
(WebCore::timingFunctionForAnimationValue):
(WebCore::GraphicsLayerAnimation::apply):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@132798 268f45cc-cd09-0410-ab3c-d52691b4dbfc