Revert "Web Animations: Avoid player updates when compositor start time is set"

Speculative revert of r171839 (79752631e5c1d483195a10a1342e953df08f6440)
[1] as it is suspected of having caused a browser_tests failure on
ChromeOS [2].

TBR=dstockwell@chromium.org

1: https://codereview.chromium.org/238353013
2: http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%282%29/builds/10673

Review URL: https://codereview.chromium.org/242023003

git-svn-id: svn://svn.chromium.org/blink/trunk@171894 bbb929c8-8fbe-4397-9dbb-9b2b20218538