Bug 1244768 part 5 - reject pending play promises while the playback reaching the end; r=jwwang

4.8.12.8
https://html.spec.whatwg.org/multipage/embedded-content.html#dom-media-ended

MozReview-Commit-ID: H7Tw0XGzpW0

dom/html/HTMLMediaElement.cpp

@@ -5146,7 +5146,12 @@ void HTMLMediaElement::PlaybackEnded()
     return;
   }
 
-  Pause();
+  FireTimeUpdate(false);
+
+  if (!mPaused) {
+    Pause();
+    AsyncRejectPendingPlayPromises(NS_ERROR_DOM_MEDIA_ABORT_ERR);
+  }
 
   if (mSrcStream) {
     // A MediaStream that goes from inactive to active shall be eligible for
@@ -5154,7 +5159,6 @@ void HTMLMediaElement::PlaybackEnded()
     mAutoplaying = true;
   }
 
-  FireTimeUpdate(false);
   DispatchAsyncEvent(NS_LITERAL_STRING("ended"));
 }