[webrtc-stats] Unpaired candidates need to be marked as local or remote

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

== Unpaired candidates need to be marked as local or remote ==
At the moment, one is supposed to figure out whether a candidate is 
local or remote based on its position in a candidate pair.

This doesn't cover the case where you have candidates that aren't 
paired with anything - for instance IPv6 local candidates when talking
 to an IPv4-only remote system.

There should be an "isRemote = false" field on RTCIceCandidateStats, 
just like we have on RTCRTPStreamStats.

Please view or discuss this issue at 
https://github.com/w3c/webrtc-stats/issues/65 using your GitHub 
account