Fix finding locale from OS on Windows

pkg/intl/intl.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.
 
 /**
  * Internationalization object providing access to message formatting objects,
  * date formatting, parsing, bidirectional text relative to a specific locale.
  */
 #library('intl');
 
@@ skipping 123 matching lines @@
   }
 
   /**
    * Return a locale name turned into xx_YY where it might possibly be
    * in the wrong case or with a hyphen instead of an underscore.
    */
   static String canonicalizedLocale(String aLocale) {
     // Locales of length < 5 are presumably two-letter forms, or else malformed.
     // Locales of length > 6 are likely to be malformed. In either case we
     // return them unmodified and if correct they will be found.
+    // We treat C as a special case, and assume it wants en_ISO for formatting.
+    // TODO(alanknight): en_ISO is probably not quite right for the C/Posix
+    // locale for formatting. Consider adding C to the formats database.
+    if (aLocale == "C") return "en_ISO";
     if ((aLocale.length < 5) || (aLocale.length > 6)) return aLocale;
     if (aLocale[2] != '-' && (aLocale[2] != '_')) return aLocale;
+    var lastRegionLetter = aLocale.length == 5 ? "" : aLocale[5].toUpperCase();
     return '${aLocale[0]}${aLocale[1]}_${aLocale[3].toUpperCase()}'
-           '${aLocale[4].toUpperCase()}';
+           '${aLocale[4].toUpperCase()}$lastRegionLetter';
   }
 
   /**
    * Support method for message formatting. Select the correct plural form from
    * [cases] given [howMany].
    */
   static String plural(var howMany, Map cases, [num offset=0]) {
     // TODO(efortuna): Deal with "few" and "many" cases, offset, and others!
     return select(howMany.toString(), cases);
   }
@@ skipping 51 matching lines @@
 /**
  * Initialize the message lookup mechanism. This is for internal use only.
  * User applications should import message_lookup_local.dart and call
  * initializeMessages
  */
 void initializeInternalMessageLookup(Function lookupFunction) {
   if (_messageLookup is UninitializedLocaleData) {
     _messageLookup = lookupFunction();
   }
 }