implement exports, fixes #141

test/codegen/language/export_cyclic_helper1.dart

Index: test/codegen/language/export_cyclic_helper1.dart
diff --git a/tool/input_sdk/lib/core/type.dart b/test/codegen/language/export_cyclic_helper1.dart
similarity index 59%
copy from tool/input_sdk/lib/core/type.dart
copy to test/codegen/language/export_cyclic_helper1.dart
index d2e107b6b183f9f674dfba4e7138c195a2d69c19..4e8a68b15cb5d03c70f353f28bd16114fc9c5c43 100644
--- a/tool/input_sdk/lib/core/type.dart
+++ b/test/codegen/language/export_cyclic_helper1.dart
@@ -2,9 +2,14 @@
 // 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.
 
-part of dart.core;
+library export_cyclic_helper1;
 
-/**
- * Runtime representation of a type.
- */
-abstract class Type {}
+import 'export_cyclic_helper2.dart';
+export 'export_cyclic_helper2.dart';
+
+class B {
+  A a;
+  B b;
+  C c;
+  D d;
+}