Deferred prefix support in metadata

tests/language/deferred_constraints_constants_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.
 
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
+import 'dart:mirrors';
 
 import "deferred_constraints_constants_lib.dart" deferred as lib;
 
 const myConst1 =
   lib.constantInstance; /// reference1: compile-time error
   /*                    /// reference1: continued
   499;
   */                    /// reference1: continued
 const myConst2 =
   lib.Const.instance; /// reference2: compile-time error
@@ skipping 30 matching lines @@
   lib.loadLibrary().then((_) {
     var instance = lib.constantInstance;
     var c1 = const lib.Const(); /// constructor1: compile-time error
     var c2 = const lib.Const.namedConstructor(); /// constructor2: compile-time error
     f1();
     f2();
     var constInstance = lib.constantInstance; /// reference_after_load: ok
     var h1 = new H1();
     var h2 = new H2();
     var h3 = new H3();
+
+    // Need to access the metadata to trigger the expected compilation error.
+    reflectClass(H1).metadata;  // metadata1: continued
+    reflectClass(H2).metadata;  // metadata2: continued
+    reflectClass(H3).metadata;  // metadata3: continued
+
     asyncEnd();
   });
 }