Remove new RTCSessionDescription pattern

SetRemoteDescription accepts a RTCSessionDescriptionInit so this is no
longer needed

Resolves #2324

examples/rtcp-processing/jsfiddle/demo.js

@@ -40,7 +40,7 @@ window.startSession = () => {
   }
 
   try {
-    pc.setRemoteDescription(new RTCSessionDescription(JSON.parse(atob(sd))))
+    pc.setRemoteDescription(JSON.parse(atob(sd)))
   } catch (e) {
     alert(e)
   }