[webrtc-pc] new commits pushed by aboba

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

* Line breaks
  by Lennart Grahl
https://github.com/w3c/webrtc-pc/commit/86c57900db9853fd3b726551d645c2e15cd6cf9f

* Mark RTCSctpTransport.maxChannels as nullable
  by Lennart Grahl
https://github.com/w3c/webrtc-pc/commit/8213649e96f41b426bd74addcd09f89756271853

* Merge pull request #1873 from lgrahl/dc-max-channels-nits-1

Make RTCSctpTransport.maxChannels nullable & line breaks
  by Bernard Aboba
https://github.com/w3c/webrtc-pc/commit/6161ca59cb0e2c4a45120152f73c6134e5dc02b6