2002 WebRTC tests #580

FYI, the https://www.privacytools.io/webrtc.html test in our wiki is 404, so I gave it a strikethru and added this one. This is also handy for 2001, but do we need to double up on it? We're only disabling WebRTC because of IP leaks, so I don't see the point in testing if WebRTC is disabled.

user.js

@@ -1040,6 +1040,7 @@ user_pref("media.peerconnection.turn.disable", true);
 user_pref("media.peerconnection.ice.tcp", false);
 user_pref("media.navigator.video.enabled", false); // video capability for WebRTC
 /* 2002: limit WebRTC IP leaks if using WebRTC
+ * [TEST] https://browserleaks.com/webrtc
  * [1] https://bugzilla.mozilla.org/buglist.cgi?bug_id=1189041,1297416
  * [2] https://wiki.mozilla.org/Media/WebRTC/Privacy ***/
 user_pref("media.peerconnection.ice.default_address_only", true); // [FF42-FF50]