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

tests/standalone/src/ProcessWorkingDirectoryTest.dart

Index: tests/standalone/src/ProcessWorkingDirectoryTest.dart
diff --git a/tests/standalone/src/ProcessWorkingDirectoryTest.dart b/tests/standalone/src/ProcessWorkingDirectoryTest.dart
index 9e14b031b522eaea3d5293c9f709aeff5cf88d70..281a8103735d360295d57c07e821ba2d96240e7d 100644
--- a/tests/standalone/src/ProcessWorkingDirectoryTest.dart
+++ b/tests/standalone/src/ProcessWorkingDirectoryTest.dart
@@ -1,10 +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.
 //
 // Process working directory test.
 
 #library("ProcessWorkingDirectoryTest");
+#import("dart:io");
 #source("ProcessTestUtil.dart");
 
 class ProcessWorkingDirectoryTest {