Fix simulcast example.

webrtc.html

@@ -11468,7 +11468,7 @@ <h3>Simulcast Example</h3>
   // let the "negotiationneeded" event trigger offer generation
   pc.onnegotiationneeded = async () =&gt; {
     try {
-      await pc.setLocalDescription(pc.createOffer());
+      await pc.setLocalDescription(await pc.createOffer());
       // send the offer to the other peer
       signaling.send(JSON.stringify({desc: pc.localDescription}));
     } catch (err) {