Bug 1382303 - P2. Do not activate autoplay early. r=jwwang

Per spec, autoplay should only gets triggered once readyState is equal to HAVE_ENOUGH_DATA

MozReview-Commit-ID: 6nW1U6G1qme

--HG--
extra : rebase_source : da46988cc75b0b5c2a87d86f55fca2fda912be55

dom/html/HTMLMediaElement.cpp

@@ -5986,8 +5986,7 @@ bool HTMLMediaElement::CanActivateAutoplay()
 
   bool hasData =
     (mDecoder && mReadyState >= nsIDOMHTMLMediaElement::HAVE_ENOUGH_DATA) ||
-    (mSrcStream && mSrcStream->Active()) ||
-    mMediaSource;
+    (mSrcStream && mSrcStream->Active());
 
   return hasData;
 }