Add mirrors tests

test/codegen/lib/mirrors/metadata_constructed_constant_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.
+
+library test.metadata_constructed_constant_test;
+
+import 'dart:mirrors';
+
+import 'package:expect/expect.dart';
+
+class ConstructedConstant {
+  final value;
+  const ConstructedConstant(this.value);
+  toString() => 'ConstructedConstant($value)';
+}
+
+class Foo {
+  @ConstructedConstant(StateError)
+  m() {}
+}
+
+main() {
+  var value =
+      reflectClass(Foo).declarations[#m].metadata.single.reflectee;
+  Expect.stringEquals('ConstructedConstant($StateError)', '$value');
+}