[webrtc-pc] legacy methods: when are they called?

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

== legacy methods: when are they called? ==
http://w3c.github.io/webrtc-pc/#legacy-interface-extensions
describes the "legacy" interface. However, there is no description for when these are called.
This decision is typically made based on the number of arguments to the function call and the type of the first argument (e.g. in createOffer)

Also: what error is thrown if the failureCallback is missing?

Please view or discuss this issue at https://github.com/w3c/webrtc-pc/issues/1231 using your GitHub account