Animation::FlushStyle() gets called only for CSS animations/transitions'
playState changes in JS or ready Promise for CSS animations. In either case
throttled animation state, which is, to be precise, transformed position or
opacity value on the compositor, doesn't affect those results.
The first test case for CSS animations and the first test case for CSS
transitions in this patch fail without this fix.
MozReview-Commit-ID: EVym4qputL4
--HG--
extra : rebase_source : 12524c7db1d59da69687bb123fc65ad4301f5527
1a43163be4