Web Animations: Start time notification should not set compositor pending
Web Animations: Start time notification should not set compositor pending

BUG=440196

Review URL: https://codereview.chromium.org/788963003

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@186829 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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