Discontinue $webrtc filters

Background

The $webrtc filter option is supported through a complex wrapper of the RTCPeerConnection API, injected into every document. This approach is a maintenance burden, and negatively effects the performance of the browser even if no $webrtc filter is active.

But you can essentially achieve the same effect of a filter like $webrtc,domain=example.com with a filter like ||example.com^$csp=webrtc-src 'none'.

What to change

Remove support for $webrtc filters.