As per an article linked in one of the comments here (http://www.smashingmagazine.com/2015/01/26/inside-microsofts...) it seems as if WebRTC 1.1 will be supported.

It supports ORTC which is sort of like WebRTC 1.5

It's backwards compatible with WebRTC so it'll work with Chrome and Firefox, but it gives you more control of the protocols so you could build something that doesn't rely on SDP.

It's in development according to https://status.modern.ie/webrtcobjectrtcapi?term=webrt