Rename WebAnimation to WebCompositorAnimation

Change WebAnimation to WebCompositorAnimation
Change WebAnimationCurve to WebCompositorAnimationCurve
Change WebAnimationDelegate to WebCompositorAnimationDelegate

This is patch 3 of 3. It builds on http://crrev.com/413983002

BUG=396358

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=179910

Review URL: https://codereview.chromium.org/412123002

git-svn-id: svn://svn.chromium.org/blink/trunk@180514 bbb929c8-8fbe-4397-9dbb-9b2b20218538