Restored the MirrorsUsed which was removed in CL 1933283002.

pkg/analyzer/test/reflective_tests.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 analyzer.test.reflective_tests;
 
 import 'dart:async';
+@MirrorsUsed(metaTargets: 'ReflectiveTest')
 import 'dart:mirrors';
 
 import 'package:unittest/unittest.dart';
 
 /**
  * A marker annotation used to annotate overridden test methods (so we cannot
  * rename them to `fail_`) which are expected to fail at `assert` in the
  * checked mode.
  */
 const _AssertFailingTest assertFailingTest = const _AssertFailingTest();
@@ skipping 152 matching lines @@
   const _AssertFailingTest();
 }
 
 /**
  * A marker annotation used to annotate overridden test methods (so we cannot
  * rename them to `fail_`) which are expected to fail.
  */
 class _FailingTest {
   const _FailingTest();
 }