fix RTCPeerConnection connectionState compat information (#2815)
fix RTCPeerConnection connectionState compat information (#2815)

not implemented anywhere. The event is not either.
Chrome: https://bugs.chromium.org/p/chromium/issues/detail?id=823144
Firefox: https://bugzilla.mozilla.org/1265827
mdn/browser-compat-data,teoli2003/browser-compat-data,chrisdavidmills/browser-compat-data,mdn/browser-compat-data,chrisdavidmills/browser-compat-data