virtual/threaded/compositing/visibility/visibility-simple-video-layer.html timeouts randomly

The current patch extends the expected results for this flaky test from Pass ImageFailure to
also include Timeout, as this is failing randomly in the bots, specially the Windows ones.

BUG=326524
NOTRY=true

Review URL: https://codereview.chromium.org/166803002

git-svn-id: svn://svn.chromium.org/blink/trunk@167203 bbb929c8-8fbe-4397-9dbb-9b2b20218538