HTMLMediaElement doesn't always send 'webkitplaybacktargetavailabilitychanged' event.
<rdar://problem/46429187>
Created attachment 369592 [details] Patch
Created attachment 369605 [details] Patch
Comment on attachment 369605 [details] Patch Clearing flags on attachment: 369605 Committed r245199: <https://trac.webkit.org/changeset/245199>
All reviewed patches have been landed. Closing bug.
Reopening to attach new patch.
Created attachment 369734 [details] Patch
Comment on attachment 369734 [details] Patch Clearing flags on attachment: 369734 Committed r245236: <https://trac.webkit.org/changeset/245236>