SMIL animation should only progress() on active documents

SMIL animation should only progress() on active documents

Before this patch, SMIL animation made progress on about-to-be destroyed
documents, where it didn't make sense.
This caused internal ASSERTs to hiccup on cases where
Blink timer was used to service next animation frame, and the timer event
was processed after document lifecycle has progressed to Stopping or
Stopped state.

This patch ensures that SMIL animations to only progress() on active
documents.

BUG=470409
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197415

[kouhei (in TOK), 2015-06-18 21:17:13]

kouhei@chromium.org changed reviewers:
+ fs@opera.com, pdr@chromium.org

[fs, 2015-06-18 23:22:35]

LGTM (that is one subtle TC BTW...)

[kouhei (in TOK), 2015-06-18 23:51:36]

On 2015/06/18 23:22:35, fs wrote:
> LGTM (that is one subtle TC BTW...)

Sorry I couldn't come up with a good one that repros this bug. This is the
minified fuzzer case.

[kouhei (in TOK), 2015-06-18 23:51:53]

The CQ bit was checked by kouhei@chromium.org

[commit-bot: I haz the power, 2015-06-18 23:52:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1178733005/1

[commit-bot: I haz the power, 2015-06-19 01:30:11]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197415