Reapply "Add a sleep function to dart:io"

runtime/bin/process_patch.dart

Index: runtime/bin/process_patch.dart
diff --git a/runtime/bin/process_patch.dart b/runtime/bin/process_patch.dart
index 4893ceef04afc92d195c335c82e74f384033a3e1..21d09b6e33b5e5c44368e8ecf1497c6df14b5262 100644
--- a/runtime/bin/process_patch.dart
+++ b/runtime/bin/process_patch.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, 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.
 
@@ -33,6 +33,7 @@ patch class Process {
 patch class _ProcessUtils {
   /* patch */ static _exit(int status) native "Process_Exit";
   /* patch */ static _setExitCode(int status) native "Process_SetExitCode";
+  /* patch */ static _sleep(int millis) native "Process_Sleep";
 }