Rationalize Dart mojo and sky package structure

sky/sdk/lib/framework/embedder.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 "package:mojo/public/dart/application.dart";
+import "package:mojo/application.dart";
 import "dart:sky.internals" as internals;
-import "package:mojo/public/dart/bindings.dart" as bindings;
-import "package:mojo/public/dart/core.dart" as core;
+import "package:mojo/bindings.dart" as bindings;
+import "package:mojo/core.dart" as core;
 import "package:mojom/mojo/service_provider.mojom.dart";
 import "package:mojom/mojo/shell.mojom.dart";
 import "package:mojom/mojo/service_registry.mojom.dart";
 
 final _EmbedderImpl embedder = new _EmbedderImpl();
 
 class _EmbedderImpl {
   ApplicationConnection _connection;
   ServiceRegistryProxy _serviceRegistry;
   ShellProxy _shell;
@@ skipping 43 matching lines @@
   }
 
   ServiceRegistryProxy get serviceRegistry {
     if (_serviceRegistry == null) {
       _serviceRegistry = new ServiceRegistryProxy.fromHandle(
           new core.MojoHandle(internals.takeServiceRegistry()));
     }
     return _serviceRegistry;
   }
 }