[webrtc-pc] new commits pushed by alvestrand

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

* pc.close() does not fire connectionstatechange either
  by Philipp Hancke
https://github.com/w3c/webrtc-pc/commit/6fd43b1ecd0fe46ee6ff95aab831bd392e11f862

* same same for signalingstate
  by Philipp Hancke
https://github.com/w3c/webrtc-pc/commit/5f9c34164b6ea9e41c0697b509f0d21bc5e7961e

* Merge pull request #2461 from fippo/dont-fire

pc.close() does not fire connectionstatechange either
  by Harald Alvestrand
https://github.com/w3c/webrtc-pc/commit/b4d01d66494dcf25e5876b549454f77997e19428