Refactor Future constructors.

sdk/lib/io/directory_impl.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.
 
 part of dart.io;
 
 class _Directory implements Directory {
   static const CREATE_REQUEST = 0;
   static const DELETE_REQUEST = 1;
   static const EXISTS_REQUEST = 2;
@@ skipping 46 matching lines @@
   // none of the directories exist dirsToCreate.length is returned.
   Future<int> _computeExistingIndex(List dirsToCreate) {
     var future;
     var notFound = dirsToCreate.length;
     for (var i = 0; i < dirsToCreate.length; i++) {
       if (future == null) {
         future = dirsToCreate[i].exists().then((e) => e ? i : notFound);
       } else {
         future = future.then((index) {
           if (index != notFound) {
-            return new Future.immediate(index);
+            return new Future.value(index);
           }
           return dirsToCreate[i].exists().then((e) => e ? i : notFound);
         });
       }
     }
     if (future == null) {
-      return new Future.immediate(notFound);
+      return new Future.value(notFound);
     } else {
       return future;
     }
   }
 
   Future<Directory> createRecursively() {
     if (_path is !String) {
       throw new ArgumentError();
     }
     var path = new Path(_path);
     var dirsToCreate = [];
     var terminator = path.isAbsolute ? '/' : '';
     while (path.toString() != terminator) {
       dirsToCreate.add(new Directory.fromPath(path));
       path = path.directoryPath;
     }
     return _computeExistingIndex(dirsToCreate).then((index) {
       var future;
       for (var i = index - 1; i >= 0 ; i--) {
         if (future == null) {
           future = dirsToCreate[i].create();
         } else {
           future = future.then((_) {
             return dirsToCreate[i].create();
           });
         }
       }
       if (future == null) {
-        return new Future.immediate(this);
+        return new Future.value(this);
       } else {
         return future.then((_) => this);
       }
     });
   }
 
   Future<Directory> create({recursive: false}) {
     if (recursive) return createRecursively();
     _ensureDirectoryService();
     List request = new List(2);
@@ skipping 209 matching lines @@
 
   void _ensureDirectoryService() {
     if (_directoryService == null) {
       _directoryService = _newServicePort();
     }
   }
 
   final String _path;
   SendPort _directoryService;
 }