Add mirrors tests

test/codegen/lib/mirrors/array_tracing2_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.
 
-// Regression test for dart2js that used to crash on type literals
-// used in a cascade send.
+import 'dart:mirrors';
 
 class A {
-  var bar;
-  var foo = {};
+  var field;
 }
 
 main() {
   var a = new A();
-  a..foo[Object] = 54
-   ..bar = 42;
-  if (a.foo.keys.first is! Type) {
-    throw 'Test failed';
-  }
+  var mirror = reflect(a);
+  var array = [42];
+  a.field = array;
+  var field = mirror.getField(#field);
+  field.invoke(#clear, []);
+  if (array.length == 1) throw 'Test failed';
 }