Remove duplicated code on Windows

runtime/bin/utils_win.h

Index: runtime/bin/utils_win.h
diff --git a/runtime/bin/io_natives.h b/runtime/bin/utils_win.h
similarity index 57%
copy from runtime/bin/io_natives.h
copy to runtime/bin/utils_win.h
index dac7fce8b9f66e5e0ee0a23be4ec524f7f1f7c46..a0447604cfee6d5545a40139e2226e2ef86fda9a 100644
--- a/runtime/bin/io_natives.h
+++ b/runtime/bin/utils_win.h
@@ -2,19 +2,17 @@
 // 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.
 
-#ifndef BIN_IO_NATIVES_H_
-#define BIN_IO_NATIVES_H_
-
-#include "include/dart_api.h"
+#ifndef BIN_UTILS_WIN_H_
+#define BIN_UTILS_WIN_H_
 
+#include "platform/globals.h"
 
 namespace dart {
 namespace bin {
 
-Dart_NativeFunction IONativeLookup(Dart_Handle name,
-                                   int argument_count);
+void FormatMessageIntoBuffer(DWORD code, wchar_t* buffer, int buffer_length);
 
 }  // namespace bin
 }  // namespace dart
 
-#endif  // BIN_IO_NATIVES_H_
+#endif  // BIN_UTILS_WIN_H_