Sky should expose services provided to/by embedder

sky/framework/shell.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import "/mojo/public/dart/application.dart";
 import "dart:mojo_bindings" as bindings;
 import "dart:mojo_core" as core;
 import "dart:sky.internals" as internals;
 import "package:mojo/public/interfaces/application/service_provider.mojom.dart";
 import "package:mojo/public/interfaces/application/shell.mojom.dart";
 
 final ShellProxy _shell = new ShellProxy.fromHandle(
-    new core.MojoHandle(internals.passShellProxyHandle()));
+    new core.MojoHandle(internals.takeShellProxyHandle()));
 
 ApplicationConnection connectToApplication(String url) {
   var serviceProviderProxy = new ServiceProviderProxy.unbound();
   _shell.connectToApplication(url, serviceProviderProxy, null);
   return new ApplicationConnection(null, serviceProviderProxy);
 }
 
 void connectToService(String url, bindings.Proxy proxy) {
   connectToApplication(url).requestService(proxy);
 }