[webrtc-pc] setRemoteDescription(): Is parameter optional or not? (#2242)

a2sheppy has just created a new issue for https://github.com/w3c/webrtc-pc:

== setRemoteDescription(): Is parameter optional or not? ==
In the WebIDL, `setRemoteDescription()` indicates that the `description` parameter is optional. However, the text doesn't seem to indicate (or, if it does, it doesn't do it clearly or in a place that's obvious).

That is, if you go to [the steps for `setLocalDescription()`](https://w3c.github.io/webrtc-pc/#dom-peerconnection-setremotedescription), you find "1. Let *description* be the method's first argument", with no explanation as to what to do if the argument is missing.

It would help to add an explicit explanation of what it means to leave out the optional parameter.

Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/2242 using your GitHub account