Gardening: The following tests are flaky on Release bots.
 - virtual/threaded/animations/3d/change-transform-in-end-event.html
 - virtual/threaded/animations/interpolation/clip-interpolation.html

BUG=248938
TBR=rjkroege@chromium.org

Review URL: https://codereview.chromium.org/23441014

git-svn-id: svn://svn.chromium.org/blink/trunk@156890 bbb929c8-8fbe-4397-9dbb-9b2b20218538