Verify the default locale in case we're given an invalid one and need to fall back.

pkg/intl/lib/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.
 
 /**
  * This library provides internationalization and localization. This includes
  * message formatting and replacement, date and number formatting and parsing,
  * and utilities for working with Bidirectional text.
  *
  * This is part of the [intl package]
@@ skipping 174 matching lines @@
    * Note that null is interpreted as meaning the default locale, so if
    * [newLocale] is null it will be returned.
    */
   static String verifiedLocale(String newLocale, Function localeExists,
                                {Function onFailure: _throwLocaleError}) {
     // TODO(alanknight): Previously we kept a single verified locale on the Intl
     // object, but with different verification for different uses, that's more
     // difficult. As a result, we call this more often. Consider keeping
     // verified locales for each purpose if it turns out to be a performance
     // issue.
-    if (newLocale == null) return getCurrentLocale();
+    if (newLocale == null) {
+      return verifiedLocale(getCurrentLocale(), localeExists,
+          onFailure: onFailure);
+    }
     if (localeExists(newLocale)) {
       return newLocale;
     }
     for (var each in
         [canonicalizedLocale(newLocale), shortLocale(newLocale)]) {
       if (localeExists(each)) {
         return each;
       }
     }
     return onFailure(newLocale);
@@ skipping 154 matching lines @@
    * unless for some reason this gets called inside a message that resets the
    * locale.
    */
   static String getCurrentLocale() {
     if (defaultLocale == null) defaultLocale = systemLocale;
     return defaultLocale;
   }
 
   toString() => "Intl($locale)";
 }