I've been observing frequent failures in the Win7 bots in the past few days due to either animations/interpolation/transform-interpolation.html or virtual/threaded/animations/interpolation/transform-interpolation.html timing out.

Recent examples:
* https://luci-milo.appspot.com/buildbot/tryserver.chromium.win/win_chromium_rel_ng/527930
* https://luci-milo.appspot.com/buildbot/tryserver.chromium.win/win_chromium_rel_ng/527939
* https://luci-milo.appspot.com/buildbot/tryserver.chromium.win/win_chromium_rel_ng/527913

This has been affecting our web-platform-tests imports lately, as win_chromium_rel_ng ends up failing and blocks the import.

The issue looks similar to  bug 669911 , so I'm filing this one for the animations team to look into. Meanwhile, I'll try marking those tests as slow.