Bug 1601422 - Update output track sources synchronously when aborted by content. r=jib

Differential Revision: https://phabricator.services.mozilla.com/D99936

dom/html/HTMLMediaElement.cpp

@@ -2300,6 +2300,7 @@ void HTMLMediaElement::AbortExistingLoads() {
     }
     ChangeNetworkState(NETWORK_EMPTY);
     RemoveMediaTracks();
+    UpdateOutputTrackSources();
     ChangeReadyState(HAVE_NOTHING);
 
     // TODO: Apply the rules for text track cue rendering Bug 865407