MediaRecorderPrivateWriter should not be destroyed until finishing its writing task completion handler is called
<rdar://problem/57561143>
Created attachment 384702 [details] Patch
Comment on attachment 384702 [details] Patch Clearing flags on attachment: 384702 Committed r253040: <https://trac.webkit.org/changeset/253040>
All reviewed patches have been landed. Closing bug.