Use patching for dart:io.

runtime/bin/directory_patch.dart

Index: runtime/bin/directory_patch.dart
diff --git a/runtime/bin/directory_patch.dart b/runtime/bin/directory_patch.dart
new file mode 100644
index 0000000000000000000000000000000000000000..6d42f8b507ac51b246395e3a5c368cef2d7a9bd3
--- /dev/null
+++ b/runtime/bin/directory_patch.dart
@@ -0,0 +1,16 @@
+// 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.
+
+patch class _Directory {
+  /* patch */ static String _current() native "Directory_Current";
+  /* patch */ static _createTemp(String template) native "Directory_CreateTemp";
+  /* patch */ static int _exists(String path) native "Directory_Exists";
+  /* patch */ static _create(String path) native "Directory_Create";
+  /* patch */ static _delete(String path, bool recursive)
+      native "Directory_Delete";
+  /* patch */ static _rename(String path, String newPath)
+      native "Directory_Rename";
+  /* patch */ static SendPort _newServicePort()
+      native "Directory_NewServicePort";
+}