[webrtc-pc] new commits pushed by alvestrand

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

* Specify how setCodecPreferences is affected by direction.
  by Henrik Boström
https://github.com/w3c/webrtc-pc/commit/eee84f465d644487e85028c77035322ea1414f81

* nit and remove unused algorithm
  by Henrik Boström
https://github.com/w3c/webrtc-pc/commit/ab858556ec87f8099d947df119cf27b6ce8c5918

* Merge pull request #2030 from henbos/181108_setCodecPreferences

Specify how codec preferences is affected by direction.
  by Harald Alvestrand
https://github.com/w3c/webrtc-pc/commit/e437c10838db4f615d5b3036d766b779cd091a15