Revert of Disable media.media_cns_cases on Mac. (https://codereview.chromium.org/
197233007/)
Reason for revert:
Test is probably fixed (http://crbug.com/339162)
Original issue's description:
> Disable media.media_cns_cases on Mac.
>
> BUG=353268
> TBR=hartmanng
>
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257643
TBR=hartmanng@chromium.org,teravest@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=353268
Review URL: https://codereview.chromium.org/
249953002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@265698 0039d316-1c4b-4281-b951-d872f2087c98