[EME][Mac] Check the underlying error if the one returned by AVFoundation is AVErrorUnknown.
Created attachment 242080 [details] Patch
Comment on attachment 242080 [details] Patch Clearing flags on attachment: 242080 Committed r176482: <http://trac.webkit.org/changeset/176482>
All reviewed patches have been landed. Closing bug.
<rdar://problem/19118302>