[webrtc-pc] new commits pushed by alvestrand

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

* Fix link to description of DataChannel send()

Move description algorithm closer to the methods themselves
Fix links from methods to description
  by Dominique Hazael-Massieux
https://github.com/w3c/webrtc-pc/commit/6613aa9338801047995b551d915f2bc2c1a78eb4

* Merge pull request #2154 from dontcallmedom/dc-send-desc

Fix link to description of DataChannel send()
  by Harald Alvestrand
https://github.com/w3c/webrtc-pc/commit/6ab20453b5b0fd6430f52790972ea9d9b71311fa