Bug 1513973 - Remove check for `false`. r=jib

The microphone source is no longer shared so this check is moot.

Differential Revision: https://phabricator.services.mozilla.com/D15192

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

dom/media/webrtc/MediaEngineWebRTCAudio.cpp

@@ -511,10 +511,6 @@ nsresult MediaEngineWebRTCMicrophoneSource::SetTrack(
   MOZ_ASSERT(aStream);
   MOZ_ASSERT(IsTrackIDExplicit(aTrackID));
 
-  if (mStream && mStream->Graph() != aStream->Graph()) {
-    return NS_ERROR_NOT_AVAILABLE;
-  }
-
   MOZ_ASSERT(!mStream);
   MOZ_ASSERT(mTrackID == TRACK_NONE);
   MOZ_ASSERT(mPrincipal == PRINCIPAL_HANDLE_NONE);