[webrtc-pc] new commits pushed by aboba

The following commits were just pushed by aboba to https://github.com/w3c/webrtc-pc:

* Add note on msids being empty on rejection.
  by Jan-Ivar Bruaroey
https://github.com/w3c/webrtc-pc/commit/61791217fb242f8694dc3c4a7ff58bec03faacbf

* Set direction="inactive" if rejected
  by Jan-Ivar Bruaroey
https://github.com/w3c/webrtc-pc/commit/2f1e865526c4a9e903e007b47ddffe9db1d4866a

* Merge pull request #2118 from jan-ivar/inactive

Set direction="inactive" if rejected
  by Bernard Aboba
https://github.com/w3c/webrtc-pc/commit/2dea877e001279fca512aa6661ee14ebd86afddc