[webrtc-pc] new commits pushed by aboba

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

* Fix type of events in datachannel description

close #2482
  by Dominique Hazael-Massieux
https://github.com/w3c/webrtc-pc/commit/50cd8c6005775928236001677fe0671b411b5f45

* Fix typo
  by Bernard Aboba
https://github.com/w3c/webrtc-pc/commit/0b6d29bcb7221debe01cf8194f213d0968fb1028

* Merge pull request #2546 from w3c/fix-event-types

Fix type of events in datachannel description
  by Bernard Aboba
https://github.com/w3c/webrtc-pc/commit/2b56445604ceb50bd5d4485716bb81b30dc45a6f