Chromium support for window.webkitRequestAnimationFrame()

This is a very simple scheduler that targets 100fps.

BUG=64848
TEST=layout tests

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=71909

Review URL: http://codereview.chromium.org/6136005

git-svn-id: http://src.chromium.org/svn/trunk/src/build@72230 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

features_override.gypi

@@ -39,6 +39,7 @@
       'ENABLE_OPENTYPE_SANITIZER=1',
       'ENABLE_ORIENTATION_EVENTS=0',
       'ENABLE_PROGRESS_TAG=1',
+      'ENABLE_REQUEST_ANIMATION_FRAME=1',
       'ENABLE_RUBY=1',
       'ENABLE_SANDBOX=1',
       'ENABLE_SHARED_WORKERS=1',