Gardening: another media test media/media-controller-playbackrate.html still failing

BUG=414649
TBR= dpranke@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/574933002

git-svn-id: svn://svn.chromium.org/blink/trunk@182135 bbb929c8-8fbe-4397-9dbb-9b2b20218538