Make --dump-render-tree's requestAnimationFrame more real

This CL adds a call to layout in --dump-render-tree's fake implementation of
requestAnimationFrame, which more closely mirrors what the real implementation
of requestAnimationFrame does. The real implementation is driven by the
compositor, which doesn't exist when running with --dump-render-tree.

R=esprehn@chromium.org
BUG=337617

Review URL: https://codereview.chromium.org/131973020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247081 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed