Add mirrors tests

test/codegen/lib/mirrors/get_field_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.
+
+@MirrorsUsed(targets: "A")
+import 'dart:mirrors';
+
+import 'package:expect/expect.dart';
+
+class A {
+  foo(y, [x]) => y;
+  operator+(other) => null;
+  get bar => 499;
+  operator$foo([optional = 499]) => optional;
+}
+
+main() {
+  // We are using `getField` to tear off `foo`. We must make sure that all
+  // stub methods are installed.
+  var closure = reflect(new A()).getField(#foo).reflectee;
+  Expect.equals("b", closure("b"));
+
+  closure = reflect(new A()).getField(#operator$foo).reflectee;
+  Expect.equals(499, closure());
+}