Find the system locale from the browser or OS

pkg/intl/intl_browser.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 provides facilities for Internationalization that are only available
+ * when running in the web browser. You should import only one of this or
+ * intl_standalone.dart. Right now the only thing provided here is the
+ * ability to find the default locale from the browser.
+ */
+
+#library("intl_browser");
+
+#import("dart:html");
+#import("intl.dart");
+
+// TODO(alanknight): The need to do this by forcing the user to specially
+// import a particular library is a horrible hack, only done because there
+// seems to be no graceful way to do this at all. Either mirror access on
+// dart2js or the ability to do spawnUri in the browser would be promising
+// as ways to get rid of this requirement.
+/**
+ * Find the system locale, accessed as window.navigator.language, and
+ * set it as the default for internationalization operations in the
+ * [Intl.systemLocale] variable.
+ */
+Future<String> findSystemLocale() {
+  Intl.systemLocale = window.navigator.language.replaceFirst("-","_");
+}