firefox: shim hyphens in getStats types
firefox: shim hyphens in getStats types

changes the types of the getStats reports from (e.g.) localcandidate
to local-candidate. Workaround until
  https://bugzilla.mozilla.org/show_bug.cgi?id=1322503
is fixed.

Acidburn0zzz/adapter,Acidburn0zzz/adapter,xdumaine/adapter,webrtc/adapter,Acidburn0zzz/adapter,jan-ivar/adapter,webrtc/adapter,jan-ivar/adapter,xdumaine/adapter