Bug 1554699 - HTMLMediaElement.preload: Ignore setting and always get "none" when playing a MediaStream. r=jib

Differential Revision: https://phabricator.services.mozilla.com/D33096

--HG--
extra : moz-landing-system : lando

dom/html/HTMLMediaElement.h

@@ -436,9 +436,16 @@ class HTMLMediaElement : public nsGenericHTMLElement,
   void NotifyAudioPlaybackChanged(AudibleChangedReasons aReason);
 
   void GetPreload(nsAString& aValue) {
+    if (mSrcAttrStream) {
+      nsGkAtoms::none->ToString(aValue);
+      return;
+    }
     GetEnumAttr(nsGkAtoms::preload, nullptr, aValue);
   }
   void SetPreload(const nsAString& aValue, ErrorResult& aRv) {
+    if (mSrcAttrStream) {
+      return;
+    }
     SetHTMLAttr(nsGkAtoms::preload, aValue, aRv);
   }