Update navigator.services API to use the new services.onconnect event [3/3].

LayoutTests/http/tests/navigatorconnect/resources/echo-worker.js

 var client;
-self.addEventListener('crossoriginconnect', function(event) {
-  client = event.client;
-  event.acceptConnection(true);
-});
-
 self.addEventListener('crossoriginmessage', function(event) {
   client.postMessage(event.data, event.ports);
 });
 
 navigator.services.addEventListener('connect', function(event) {
   event.respondWith({accept: true}).then(function(port) { client = port; });
 });