Bug 209242

According to the spec example https://w3c.github.io/webrtc-pc/#simple-peer-to-peer-example the following should work, but does not work in Safari:

  pc.ontrack = ({track, streams}) => {
    // once media for a remote track arrives, show it in the remote video element
    track.onunmute = () => {
      // don't set srcObject again if it is already set.
      if (remoteView.srcObject) return;
      remoteView.srcObject = streams[0];
    };
  };

STRs:
 1. Open https://blog.mozilla.org/webrtc/rtcrtptransceiver-explored/ and scroll down and click the "Result" button in the first jsfiddle
    (or use direct link: https://jsfiddle.net/jib1/z0desL8x/89/show )
 2. Share camera and microphone
 3. Click the first Remote control button to add a transceiver.

Expected result (like Chrome, Firefox & Edge):

  pc.ontrack with transceiver and streams
  transceiver.receiver.track.onunmute

Actual result (like Chrome, Firefox & Edge):

  pc.ontrack with transceiver and streams


In the other browsers, tracks surfaced in pc.ontrack are in muted state, and the unmute event fires on them when their packets first arrive.
In Safari, tracks surfaced in pc.ontrack are instead in unmuted state, and no unmute event ever fires when their packets first arrive.

This is a web compat issue.

https://wpt.fyi/results/webrtc/RTCPeerConnection-remote-track-mute.https.html?label=experimental&label=master&aligned