Fix Failure=>ImageOnlyFailure for media/video tests.

TBR=scherkus
BUG=365857

Review URL: https://codereview.chromium.org/442113002

git-svn-id: svn://svn.chromium.org/blink/trunk@179533 bbb929c8-8fbe-4397-9dbb-9b2b20218538