Add mirrors tests

test/codegen/lib/mirrors/mirrors_used_get_name_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.
+
+// Test to make sure that the names of classes that are marked with mirrors-used
+// are preserved.
+// In the test the class B is not instantiated, but we still want its names (the
+// "foo") to be preserved.
+
+@MirrorsUsed(targets: "B")
+import 'dart:mirrors';
+import 'package:expect/expect.dart';
+
+class A {
+  noSuchMethod(invocationMirror) {
+    return MirrorSystem.getName(invocationMirror.memberName);
+  }
+}
+
+class B {
+  foo() => 499;
+}
+
+void main() {
+  var a = new A();
+  if (new DateTime.now().year == 1984) {
+    a = A;
+  }
+  Expect.equals("foo", a.foo());
+}