Add mirrors tests

test/codegen/lib/mirrors/private_class_field_other.dart

Index: test/codegen/lib/mirrors/private_class_field_other.dart
diff --git a/test/codegen/language/export_order_helper2.dart b/test/codegen/lib/mirrors/private_class_field_other.dart
similarity index 70%
copy from test/codegen/language/export_order_helper2.dart
copy to test/codegen/lib/mirrors/private_class_field_other.dart
index 2c462a4ed59e8bb3f6f74ee3b6aace81db32b274..85238b6009d14d7ee0a4b500df90e863f8896fa3 100644
--- a/test/codegen/language/export_order_helper2.dart
+++ b/test/codegen/lib/mirrors/private_class_field_other.dart
@@ -2,10 +2,8 @@
 // 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.
 
-import 'export_order_helper1.dart';
-
-class Info {
-  int x = y;
+class C {
+  static var _privateField = 42;
 }
 
-int get z => 38;
+get privateFieldSymbolInOther => #_privateField;