Web Animations: Fix Player's timing update when source content becomes longer

Web Animations: Fix Player's timing update when source content becomes longer

A Player's hold time may become unlimited when the source content changes,
special care is required to adjust the current time in this case as the
existing start time should be maintained.

CSS Animations required an additional fix, as the inert animation used for
sampling in the same recalc that could update the timing properties of an
animation, used a stale currentTime value which would be limited by the
the previous timing data.

BUG=461691
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=191073

[dstockwell, 2015-02-26 23:20:23]

dstockwell@chromium.org changed reviewers:
+ samli@chromium.org

[samli, 2015-02-27 00:49:45]

lgtm, should add a test?

[dstockwell, 2015-03-02 00:21:36]

The CQ bit was checked by dstockwell@chromium.org

[dstockwell, 2015-03-02 00:21:37]

The patchset sent to the CQ was uploaded after l-g-t-m from samli@chromium.org
Link to the patchset: https://codereview.chromium.org/961993003/#ps20001 (title:
"test")

[commit-bot: I haz the power, 2015-03-02 00:21:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/961993003/20001

[commit-bot: I haz the power, 2015-03-02 02:50:20]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=191073