Dart: Renames dart:mojo_blah -> mojo:blah

mojo/dart/test/interface_test.dart

 // Copyright 2014 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:async';
 import 'dart:isolate';
-import 'dart:mojo_bindings' as bindings;
-import 'dart:mojo_core' as core;
 import 'dart:typed_data';
+import 'mojo:bindings' as bindings;
+import 'mojo:core' as core;
 
 import 'package:mojo/dart/testing/expect.dart';
 
 const int kEchoesCount = 100;
 
 class EchoString extends bindings.Struct {
   static const int kStructSize = 16;
   static const bindings.StructDataHeader kDefaultStructInfo =
       const bindings.StructDataHeader(kStructSize, 1);
   String a = null;
@@ skipping 160 matching lines @@
     Expect.equals("Hello", response.a);
   }
   proxy.close();
 }
 
 
 main() async {
   Expect.equals(kEchoesCount, await runTest());
   await runAwaitTest();
 }