Bug 1280814 - Prevent the media::Interval crash due to the unexpected playback position. r=rillian

MozReview-Commit-ID: AZ9Gb2Y0wDF

dom/html/HTMLMediaElement.cpp

@@ -797,6 +797,10 @@ void HTMLMediaElement::AbortExistingLoads()
   AddRemoveSelfReference();
 
   mIsRunningSelectResource = false;
+
+  if (mTextTrackManager) {
+    mTextTrackManager->NotifyReset();
+  }
 }
 
 void HTMLMediaElement::NoSupportedMediaSourceError()