Add a sleep function to dart:io

runtime/platform/platform_os_win.cc

-// 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.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>  // NOLINT
+#include "platform/platform_os.h"
 
-BOOL APIENTRY DllMain(HMODULE module,
-                      DWORD  reason,
-                      LPVOID reserved) {
-  return true;
+namespace platform {
+
+void OS::Sleep(int64_t millis) {
+  ::Sleep(millis);
 }
 
+}  // namespace platform
+
 #endif  // defined(TARGET_OS_WINDOWS)