Move Keyframe and AnimationEffect to oilpan's heap

This CL moves Keyframe, AnimationEffect and KeyframeEffectModel to oilpan's heap.

BUG=340522

Review URL: https://codereview.chromium.org/177813002

git-svn-id: svn://svn.chromium.org/blink/trunk@167694 bbb929c8-8fbe-4397-9dbb-9b2b20218538