[webrtc-pc] Pull Request: Properly sort simulcast layers in example by size

Orphis has just submitted a new pull request for https://github.com/w3c/webrtc-pc:

== Properly sort simulcast layers in example by size ==
Layers should be sorted by size, with the smaller ones first as they usually have a higher priority.

See https://github.com/w3c/webrtc-pc/pull/2267