Revert "[dart:io] Adds Platform.localeName"

runtime/bin/platform_unsupported.cc

 // Copyright (c) 2016, 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.
 
 #if defined(DART_IO_DISABLED)
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 #include "include/dart_api.h"
 
@@ skipping 46 matching lines @@
   Dart_ThrowException(DartUtils::NewInternalError(
       "Platform is not supported on this platform"));
 }
 
 
 void FUNCTION_NAME(Platform_GetVersion)(Dart_NativeArguments args) {
   Dart_ThrowException(DartUtils::NewInternalError(
       "Platform is not supported on this platform"));
 }
 
-
-void FUNCTION_NAME(Platform_LocaleName)(Dart_NativeArguments args) {
-  Dart_ThrowException(DartUtils::NewInternalError(
-      "Platform is not supported on this platform"));
-}
-
 }  // namespace bin
 }  // namespace dart
 
 #endif  // !defined(DART_IO_DISABLED)