Web Animations: Remove didTriggerStyleRecalc from Player::update

This patch removes the plumbing of didTriggerStyleRecalc from the
code around updating players and timed items. The flag is used to
decide if we want to unfreeze the animation clock, which normally
happens after a style recalc.

I have removed the tests for this boolean in this patch. Correctly
testing the behaviour requires a bit of set up. When we later have
an internals api to count style recalcs, we can test the behaviour
with layout tests.

For more context crrev.com/46043014 added the flag originally.

BUG=334937

Review URL: https://codereview.chromium.org/162553003

git-svn-id: svn://svn.chromium.org/blink/trunk@167323 bbb929c8-8fbe-4397-9dbb-9b2b20218538