We should register our Legible Output notifications to run on the notification queue, rather than the main queue. If we don't we can sometimes run into shutdown problems where video playback does not end when we release the media resource because the main dispatch queue continues to run as long as the application those. This causes these resources to be held onto, resulting in media not stopping and preventing WebKit from exiting when the program is shut down.
<rdar://problem/15358129>
Created attachment 215585 [details] Patch
Committed r158334: <http://trac.webkit.org/changeset/158334>