Move all tests using dart:io to a separate directory

tests/standalone/test_config.dart

Index: tests/standalone/test_config.dart
diff --git a/tests/standalone/test_config.dart b/tests/standalone/test_config.dart
index df769f007c2af1ed4aada6791492cfae55a999c1..fc42032189839195e94a827714e853408b33cc4e 100644
--- a/tests/standalone/test_config.dart
+++ b/tests/standalone/test_config.dart
@@ -1,4 +1,4 @@
-// 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.
 
@@ -12,4 +12,6 @@ class StandaloneTestSuite extends StandardTestSuite {
               "standalone",
               "tests/standalone/src",
               ["tests/standalone/standalone.status"]);
+
+  bool listRecursively() => true;
 }