Split dart:builtin into dart:builtin and dart:io.

tests/stub-generator/test_config.dart

Index: tests/stub-generator/test_config.dart
diff --git a/tests/stub-generator/test_config.dart b/tests/stub-generator/test_config.dart
index 8d1f2887668f8c0276aea69e9c8c6252adf640cb..bb8c3de7fd6faff3fe9b213d73aa7055ac347d80 100644
--- a/tests/stub-generator/test_config.dart
+++ b/tests/stub-generator/test_config.dart
@@ -1,9 +1,11 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2012, 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.
 
 #library("stub_generator_test_config");
 
+#import("dart:io");
+
 #import("../../tools/testing/dart/test_suite.dart");
 
 class StubGeneratorTestSuite extends StandardTestSuite {