When cancelling an animation, add missing timeline-detach check.

When cancelling an animation, add missing timeline-detach check.

If the animation timeline becomes unreferenced and is destructed,
it detaches from its associated animations. Check that timeline
detach status should cancel() be called on an animation.

R=loyso,dstockwell
BUG=491847
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196299

[sof, 2015-05-31 18:25:25]

sigbjornf@opera.com changed reviewers:
+ dstockwell@chromium.org, loyso@chromium.org

[sof, 2015-05-31 18:25:26]

please take a look.

[loyso (OOO), 2015-06-01 01:50:31]

On 2015/05/31 18:25:26, sof wrote:
> please take a look.
Non-owner Looks Good To Me.

[dstockwell, 2015-06-02 00:13:19]

lgtm

[sof, 2015-06-02 05:37:54]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-06-02 05:38:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1154423006/20001

[commit-bot: I haz the power, 2015-06-02 08:32:41]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196299