[webrtc-stats] RTCPeerConnectionStats is missing state stats (connection, ice, gathering, signaling) (#484)

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

== RTCPeerConnectionStats is missing state stats (connection, ice, gathering, signaling) ==
[RTCPeerConnectionStats](https://w3c.github.io/webrtc-stats/#pcstats-dict*) does not contain PC state information.

- If we fix #483 we have iceState on a per-transport basis. Would it make sense to compute [iceConnectionState](https://w3c.github.io/webrtc-pc/#dom-peerconnection-ice-connection-state) and expose it on the PC level?
- Should we also expose [connectionState](https://w3c.github.io/webrtc-pc/#dom-peerconnection-connection-state)?
- Should we expose [iceGatheringState](https://w3c.github.io/webrtc-pc/#dom-peerconnection-ice-gathering-state)?
- Should we expose [signalingState](https://w3c.github.io/webrtc-pc/#dom-peerconnection-signaling-state)?

Please view or discuss this issue at https://github.com/w3c/webrtc-stats/issues/484 using your GitHub account