Oilpan: adjust AnimationTimeline finalization.

Oilpan: adjust AnimationTimeline finalization.

With Oilpan, explicitly disconnecting its animation players is not needed;
the ExecutionContext's weak reference will be transparently take care of
this instead.

While here, merge the timeline finalization steps into a detach operation
for AnimationPlayer.

TBR=dstockwell,oilpan-reviews
BUG=472307
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=193552

[sof, 2015-04-10 13:03:43]

sigbjornf@opera.com changed reviewers:
+ dstockwell@chromium.org, oilpan-reviews@chromium.org

[sof, 2015-04-10 13:03:46]

Please take a look.

[sof, 2015-04-10 14:21:51]

tbr'ing based on https://codereview.chromium.org/1054823002/#msg12 + bot
redness.

[sof, 2015-04-10 14:21:55]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-04-10 14:22:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1080523002/1

[commit-bot: I haz the power, 2015-04-10 14:53:49]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=193552

[haraken, 2015-04-10 16:08:41]

LGTM