We should not be providing identity assertions on sessions that contain media that has been seen or touched by a site. This gets tricky because it also means that we need to block the addition (or at least transmission) of un-constrained tracks, either those that are added via new streams or via tracks that are added to streams. It also means that you can't remove the peerIdentity constraint from a stream once it is attached to an RTCPeerConnection.

Not going to do this. We want to be able to surface identity information, even if a site doesn't request isolated media.