Fix accessing dart:_ libraries via exports.

tests/language/export_private_test.dart

Index: tests/language/export_private_test.dart
diff --git a/tests/language/import_private_test.dart b/tests/language/export_private_test.dart
similarity index 67%
copy from tests/language/import_private_test.dart
copy to tests/language/export_private_test.dart
index 85eccde9718c15178fca60a041614edeb72594ba..52b3f028bd5605c274b073843ced7a3bc9ab236c 100644
--- a/tests/language/import_private_test.dart
+++ b/tests/language/export_private_test.dart
@@ -1,9 +1,9 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2015, 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.
 // Check that private dart:_ libraries cannot be imported.
 
-import "dart:_internal";  /// 01: compile-time error
+export "dart:_internal";  /// 01: compile-time error
 
 main() {
   print("Done.");