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

sdk/lib/io/platform_impl.dart

Index: sdk/lib/io/platform_impl.dart
diff --git a/sdk/lib/io/platform_impl.dart b/sdk/lib/io/platform_impl.dart
index e5de17d02e52d6d18fe867ad5b0ac19a0c035c63..5f68b7dbdef6ded8dc6ddaf263e8090d5ae94326 100644
--- a/sdk/lib/io/platform_impl.dart
+++ b/sdk/lib/io/platform_impl.dart
@@ -32,25 +32,12 @@ class _Platform {
   external static String _packageRoot();
   external static String _packageConfig();
   external static String _version();
-  external static String _localeName();
 
   static String executable = _executable();
   static String resolvedExecutable = _resolvedExecutable();
   static String packageRoot = _packageRoot();
   static String packageConfig = _packageConfig();
 
-  static String _cachedLocaleName;
-  static String get localeName {
-    if (_cachedLocaleName == null) {
-      var result = _localeName();
-      if (result is OSError) {
-        throw result;
-      }
-      _cachedLocaleName = result;
-    }
-    return _cachedLocaleName;
-  }
-
   // Cache the OS environment. This can be an OSError instance if
   // retrieving the environment failed.
   static var /*OSError|Map<String,String>*/ _environmentCache;