implement exports, fixes #141

test/codegen/language/export_main_override_test.dart

Index: test/codegen/language/export_main_override_test.dart
diff --git a/tool/input_sdk/private/mirror_helper.dart b/test/codegen/language/export_main_override_test.dart
similarity index 56%
copy from tool/input_sdk/private/mirror_helper.dart
copy to test/codegen/language/export_main_override_test.dart
index f78926acc01ed7ad59d8563665422ef27b47321b..65782884947842267edc0df6aa350271a0b31bfc 100644
--- a/tool/input_sdk/private/mirror_helper.dart
+++ b/test/codegen/language/export_main_override_test.dart
@@ -1,8 +1,9 @@
 // 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.
-/**
- * Helps dealing with reflection in the case that the source code has been
- * changed as a result of compiling with dart2dart.
- */
-library dart._mirror_helper;
+
+export 'top_level_entry_test.dart';
+
+main() {
+  print('export_main_override');
+}