Fix AnimationEffect.accumulate after 542502c33dbaf6101e2cedcd01e087855b95f067

Also add some tests

(cherry picked from commit 9463abbdd7427d7f04ab9c62ff469604031d54b4)
Signed-off-by: Douglas Stockwell <dstockwell@chromium.org>
Fix re-ticks when setting composite on animation effects

See 542502c33dbaf6101e2cedcd01e087855b95f067

(cherry picked from commit 5d53c9aa0d9fb8f67d39795f060a902621479838)
Signed-off-by: Douglas Stockwell <dstockwell@chromium.org>
Fix bug in normalizeKeyframeDictionary()

(cherry picked from commit fceba09fa64c3ca2dddff94468ef753d454c173a)
Signed-off-by: Douglas Stockwell <dstockwell@chromium.org>
Implement KeyframeAnimationEffect.get/setFrames()

(cherry picked from commit cb5205a85c995d96b79d2964b5b5589bb516b136)
Signed-off-by: Douglas Stockwell <dstockwell@chromium.org>