Suppress 10.9 media/gc-while-playing.html failure

after r182247, so that we can investigate it

TBR=philipj@opera.com, jochen@chromium.org, kbr@chromium.org
BUG=400659

Review URL: https://codereview.chromium.org/578243003

git-svn-id: svn://svn.chromium.org/blink/trunk@182255 bbb929c8-8fbe-4397-9dbb-9b2b20218538