Added support for exports and re-exports.

tests/language/export_cyclic_helper1.dart

Index: tests/language/export_cyclic_helper1.dart
diff --git a/tests/language/compile_time_constant9_test.dart b/tests/language/export_cyclic_helper1.dart
similarity index 63%
copy from tests/language/compile_time_constant9_test.dart
copy to tests/language/export_cyclic_helper1.dart
index a149c43f11c1b94efb802fbad0ac84b423695504..4e8a68b15cb5d03c70f353f28bd16114fc9c5c43 100644
--- a/tests/language/compile_time_constant9_test.dart
+++ b/tests/language/export_cyclic_helper1.dart
@@ -2,15 +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.
 
-class B {
-  const B();
-}
+library export_cyclic_helper1;
 
-class A {
-  var x = const B();
-  A();
-}
+import 'export_cyclic_helper2.dart';
+export 'export_cyclic_helper2.dart';
 
-main() {
-  Expect.isTrue(new A().x === new A().x);
+class B {
+  A a;
+  B b;
+  C c;
+  D d;
 }