Port metrics to RPC

runtime/observatory/test/mirror_references_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library vm_references_test;
 
-import 'dart:async';
 import 'dart:mirrors';
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
 class Foo { }
 
 Foo foo;
 var /*MirrorReference*/ ref;
 
@@ skipping 20 matching lines @@
     return ref.load().then((Instance loadedRef) {
       expect(loadedRef.referent, isNotNull);
       expect(loadedRef.referent.name, equals('Foo'));
       expect(loadedRef.referent, equals(foo.clazz));
     });
   }),
 
 ];
 
 main(args) => runIsolateTests(args, tests, testeeBefore: script);