Dart: Renames dart:mojo_blah -> mojo:blah

sky/tests/services/iframe-embed-vmc.sky

 <sky>
 
 <iframe></iframe>
 
 <script>
 import 'dart:async';
-import 'dart:mojo_bindings';
-import 'dart:mojo_core';
 import 'dart:sky';
 import 'dart:sky.internals' as internals;
 import 'dart:typed_data';
 import '/mojo/public/dart/application.dart';
+import 'mojo:bindings';
+import 'mojo:core';
 
 import 'package:mojo/public/interfaces/application/shell.mojom.dart' as shell_mojom;
 import 'package:mojo/services/input_events/public/interfaces/input_events.mojom.dart' as input_events;
 import 'package:mojo/services/view_manager/public/interfaces/view_manager.mojom.dart' as view_manager;
 import 'package:services/js/test/echo_service.mojom.dart' as echo_service_mojom;
 
 class IFrameEmbed extends Application {
   IFrameEmbed.fromHandle(MojoHandle handle) : super.fromHandle(handle);
   IFrameEmbed(MojoMessagePipeEndpoint endpoint) : super(endpoint);
 
   void initialize(List<String> args, String url) {
     // The vmcApp provides ViewManagerClient and EchoService.
     const vmcURL =
         "http://127.0.0.1:8000/sky/tests/services/resources/iframe-vmc.js";
     final vmcAppConnection = connectToApplication(vmcURL);
 
-    // The Promise returned by the vmcApp's echoString() method will not 
+    // The Promise returned by the vmcApp's echoString() method will not
     // resolve until the vmcApp's onEmbed() method runs.
     final echoService = new echo_service_mojom.EchoServiceProxy.unbound();
     vmcAppConnection.requestService(echoService);
     echoService.echoString("success").then((response) {
       internals.notifyTestComplete(response.value);
     });
 
     var applicationPipe = new MojoMessagePipe();
     var proxyEndpoint = applicationPipe.endpoints[0];
     var applicationEndpoint = applicationPipe.endpoints[1];
     vmcAppConnection.remoteServiceProvider.connectToService(
         view_manager.ViewManagerClient.name, applicationEndpoint);
     document.querySelector("iframe").
         embedViewManagerClient(proxyEndpoint.handle.h);
   }
 }
 
 main() {
   var messagePipe = new MojoMessagePipe();
   var app = new IFrameEmbed(messagePipe.endpoints[1]);
   app.listen();
   var shellProxy = new shell_mojom.ShellProxy.fromHandle(
       new MojoHandle(internals.takeShellProxyHandle()));
   app.initializeFromShellProxy(shellProxy, [], "");
 }
 </script>
 </sky>