Mojo JS Bindings: Eliminate foo$ Stub and Proxy class members

examples/js/wget.js

 #!mojo:js_content_handler
 // Demonstrate use of the Mojo network service to load a URL. To run this
 // application with mojo_shell, set DIR to be the absolute path for this
 // directory, then:
 //   mojo_shell "file://$DIR/wget.js http://www.google.com"
 // Substitute any URL for google.com. To keep the noise down, this app
 // only displays the number of bytes read and a little http header info.
 
 define("main", [
   "console",
   "mojo/services/public/js/application",
   "mojo/public/js/core",
   "mojo/services/network/public/interfaces/network_service.mojom",
   "mojo/services/network/public/interfaces/url_loader.mojom",
 ], function(console, appModule, coreModule, netModule, loaderModule) {
 
   class WGet extends appModule.Application {
     initialize(args) {
       if (args.length != 2) {
         console.log("Expected URL argument");
         return;
       }
 
       var netService = this.shell.connectToService(
         "mojo:network_service", netModule.NetworkService);
 
-      var urlLoaderClient = {};
-      netService.createURLLoader(urlLoaderClient);
-      var urlLoader = urlLoaderClient.remote$;
+      var urlLoader;
+      netService.createURLLoader(function(x){urlLoader = x;});
 
       var urlRequest = new loaderModule.URLRequest({
         url: args[1],
         method: "GET",
         auto_follow_redirects: true
       });
 
       var app = this;
       urlLoader.start(urlRequest).then(function(result) {
         console.log("url => " + result.response["url"]);
         console.log("status_line => " + result.response["status_line"]);
         console.log("mime_type => " + result.response["mime_type"]);
 
         coreModule.drainData(result.response.body).then(
           function(result) {
             console.log("read " + result.buffer.byteLength + " bytes");
           })
           .then(function() {
             app.quit();
           });
       });
     }
   }
 
   return WGet;
 });