Refactor Future constructors.

pkg/intl/lib/intl_standalone.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 standalone. You should import only one of this or
  * intl_browser.dart. Right now the only thing provided here is finding
  * the operating system locale.
  */
@@ skipping 25 matching lines @@
   // On *nix systems we expect this is an environment variable, which is the
   // easiest thing to check. On a Mac the environment variable may be present
   // so always check it first. We have no mechanism for this right now on
   // Windows, so it will just fail.
   String baseLocale = _checkEnvironmentVariable();
   if (baseLocale != null) return _setLocale(baseLocale);
   if (Platform.operatingSystem == 'macos') {
     return _getAppleDefaults();
   }
   // We can't find anything, don't set the system locale and return null.
-  return new Future.immediate(null);
+  return new Future.value();
 }
 
 /**
  * Regular expression to match the expected output of reading the defaults
  * database for AppleLanguages on Mac systems.
  * e.g. {
  *     en,
  *     "pt-PT",
  *     ...
  */
@@ skipping 19 matching lines @@
   var myResult = p.then((result) => _checkResult(result, _appleDefaultsRegex));
   return myResult;
 }
 
 /**
  * Given [result], find its text and extract the locale from it using
  * [regex], and set it as the system locale. If the process didn't run correctly
  * then don't set the variable and return a future that completes with null.
  */
 Future<String> _checkResult(ProcessResult result, RegExp regex) {
-  if (result.exitCode != 0) return new Future.immediate(null);
+  if (result.exitCode != 0) return new Future.value();
   var match = regex.firstMatch(result.stdout);
-  if (match == null) return new Future.immediate(null);
+  if (match == null) return new Future.value();
   var locale = match.group(1);
   _setLocale(locale);
-  return new Future.immediate(locale);
+  return new Future.value(locale);
 }
 
 /**
  * Set [Intl.systemLocale] to be the canonicalizedLocale of [aLocale].
  */
 Future<String> _setLocale(aLocale) {
   Intl.systemLocale = Intl.canonicalizedLocale(aLocale);
-  return new Future.immediate(Intl.systemLocale);
+  return new Future.value(Intl.systemLocale);
 }