Update references to Mojo core and bindings

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 "dart:sky.internals" as internals;
 import "package:mojo/public/dart/application.dart";
-import "dart:sky.internals" as internals;
-import "dart:mojo.core" as core;
 import "package:mojo/public/interfaces/application/service_provider.mojom.dart";
+import 'package:mojo/public/dart/core.dart' as core;
 
 ApplicationConnection _initConnection() {
   int rawHandle = internals.takeServicesProvidedByEmbedder();
   core.MojoHandle proxyHandle = new core.MojoHandle(rawHandle);
   ServiceProviderProxy serviceProvider = null;
   if (proxyHandle.isValid)
     serviceProvider = new ServiceProviderProxy.fromHandle(proxyHandle);
   return new ApplicationConnection(null, serviceProvider);
 }
 
 final ApplicationConnection _connection = _initConnection();
 
 void requestService(Object proxy) {
   _connection.requestService(proxy);
 }