Add mirrors tests

test/codegen/lib/mirrors/regress_16321_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.
+
+// Regression test for Issue 16321.
+// (Type errors in metadata crashed the VM in checked mode).
+
+import "dart:mirrors";
+
+class TypedBox {
+  final List<String> contents;
+  const TypedBox(this.contents);
+}
+
+@TypedBox('foo')  /// 01: static type warning, checked mode compile-time error
+@TypedBox(const ['foo'])
+class C {}
+
+main() {
+  reflectClass(C).metadata;
+}