[webrtc-pc] new commits pushed by alvestrand

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

* Allow addIceCandidate(null) again for backwards comp and symmetry.
  by Jan-Ivar Bruaroey
https://github.com/w3c/webrtc-pc/commit/3a12c759b280bf2c64a13603e76f6b067d4e2f77

* Add note on addIceCandidate(null)
  by Jan-Ivar Bruaroey
https://github.com/w3c/webrtc-pc/commit/8f243e6e83a971783f033c1be9ccd4813701a124

* Add more notes about end-of-candidates, and fix candidate naming.
  by Jan-Ivar Bruaroey
https://github.com/w3c/webrtc-pc/commit/1f50e715da6be7902aec040a8973ccd1311cfde8

* Merge pull request #2040 from jan-ivar/addnull

Allow addIceCandidate(null) again for backwards comp and symmetry.
  by Harald Alvestrand
https://github.com/w3c/webrtc-pc/commit/75333c8f241f9e23d41422243653d0ca4d4b304a