Backed out 2 changesets (bug 1547784) for crashtest failrues on 1547784.html . CLOSED TREE

Backed out changeset 21f0da4d5763 (bug 1547784)
Backed out changeset 54b3b878f07d (bug 1547784)

dom/html/HTMLMediaElement.cpp

@@ -4670,14 +4670,6 @@ nsresult HTMLMediaElement::FinishDecoderSetup(MediaDecoder* aDecoder) {
   // This will also do an AddRemoveSelfReference.
   NotifyOwnerDocumentActivityChanged();
 
-  if (!mDecoder) {
-    // NotifyOwnerDocumentActivityChanged may shutdown the decoder if the
-    // owning document is inactive and we're in the EME case. We could try and
-    // handle this, but at the time of writing it's a pretty niche case, so just
-    // bail.
-    return NS_ERROR_FAILURE;
-  }
-
   if (mPausedForInactiveDocumentOrChannel) {
     mDecoder->Suspend();
   }