Add mirrors tests

test/codegen/lib/mirrors/library_metadata2_lib2.dart

Index: test/codegen/lib/mirrors/library_metadata2_lib2.dart
diff --git a/test/codegen/language/missing_part_of_tag_part.dart b/test/codegen/lib/mirrors/library_metadata2_lib2.dart
similarity index 89%
copy from test/codegen/language/missing_part_of_tag_part.dart
copy to test/codegen/lib/mirrors/library_metadata2_lib2.dart
index c4618bc60b69a7cac8d7ddacd25c37ea3840f96a..b8a447f07f4d6e8fc72dfa3825ff0d8d76c6e895 100644
--- a/test/codegen/language/missing_part_of_tag_part.dart
+++ b/test/codegen/lib/mirrors/library_metadata2_lib2.dart
@@ -1,3 +1,6 @@
 // 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.
+
+@MyConst()
+library lib2;