[dart:io] Reland: Adds Platform.localeName

runtime/bin/platform_patch.dart

 // 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 _Platform {
   @patch
   static int _numberOfProcessors() native "Platform_NumberOfProcessors";
   @patch
   static String _pathSeparator() native "Platform_PathSeparator";
   @patch
   static String _operatingSystem() native "Platform_OperatingSystem";
   @patch
   static _localHostname() native "Platform_LocalHostname";
   @patch
   static _executable() native "Platform_ExecutableName";
   @patch
   static _resolvedExecutable() native "Platform_ResolvedExecutableName";
   @patch
   static _environment() native "Platform_Environment";
   @patch
   static List<String> _executableArguments()
       native "Platform_ExecutableArguments";
   @patch
   static String _version() native "Platform_GetVersion";
 
   @patch
+  static String _localeName() native "Platform_LocaleName";
+
+  @patch
   static String _packageRoot() => VMLibraryHooks.packageRootString;
   @patch
   static String _packageConfig() => VMLibraryHooks.packageConfigString;
 
   // This script singleton is written to by the embedder if applicable.
   static void set _nativeScript(String path) {
     if (path.startsWith('http:') ||
         path.startsWith('https:') ||
         path.startsWith('package:') ||
         path.startsWith('dart:') ||
         path.startsWith('data:') ||
         path.startsWith('file:')) {
       script = Uri.parse(path);
     } else {
       script = Uri.base.resolveUri(new Uri.file(path));
     }
     VMLibraryHooks.platformScript = script;
   }
 }