Revert of Rename WebAnimation to WebCompositorAnimation (patchset #5 of https://codereview.chromium.org/412123002/)

Reason for revert:
BUG=402897

TBR=samli@chromium.org, jochen@chromium.org, vollick@chromium.org

Original issue's description:
> 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/467123002

git-svn-id: svn://svn.chromium.org/blink/trunk@180155 bbb929c8-8fbe-4397-9dbb-9b2b20218538