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

tests/standalone/src/PlatformTest.dart

Index: tests/standalone/src/PlatformTest.dart
diff --git a/tests/standalone/src/PlatformTest.dart b/tests/standalone/src/PlatformTest.dart
index 8796c65b2791122987422ccba788f76a13b9bc4b..bdade90b63bd810505d6113fbd125e54c1b76e25 100644
--- a/tests/standalone/src/PlatformTest.dart
+++ b/tests/standalone/src/PlatformTest.dart
@@ -1,7 +1,9 @@
-// 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.
 
+#import("dart:io");
+
 main() {
   var p = new Platform();
   Expect.isTrue(p.numberOfProcessors() > 0);