Resolve metadata on library tags

tests/lib/mirrors/library_metatarget_test.dart

 // Copyright (c) 2013, 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.
 
-// Test abstract classes are retained.
+// Regression test for the combined use of metatargets and library tags.
 
-library test.abstract_test;
+library topLib;
 
+import 'library_metatarget_test_lib.dart';
+import 'library_metatarget_test_annotations_lib.dart';
+
+@MirrorsUsed(metaTargets:const [Reflectable])
 import 'dart:mirrors';
 
-import 'stringify.dart';
-
-abstract class Foo {
+void main() {
+  print(new A());
 }
-
-void main() {
-  expect('Class(s(Foo) in s(test.abstract_test), top-level)',
-         reflectClass(Foo));
-}