[webrtc-pc] new commits pushed by alvestrand

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

* Freeze version of respec-w3c-common.js

Partial fix for Issue https://github.com/w3c/webrtc-pc/issues/942
  by Bernard Aboba
https://github.com/w3c/webrtc-pc/commit/edd562b4163d1b2518d6085d69a8a5d1eedf75e1

* Merge pull request #1007 from w3c/issue-942-patch

Freeze version of respec-w3c-common.js
  by Harald Alvestrand
https://github.com/w3c/webrtc-pc/commit/f7cc12a1f9548af23a47fb5f6c92bdd575b9aadf