Refactor Future constructors.

tests/html/fileapi_test.dart

 library fileapi;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 import 'dart:async';
 
 class FileAndDir {
   FileEntry file;
   DirectoryEntry dir;
   FileAndDir(this.file, this.dir);
@@ skipping 81 matching lines @@
 
   // Do the boilerplate to get several files and directories created to then
   // test the functions that use those items.
   Future doDirSetup() {
     return fs.root.createFile(
       'file4')
         .then((FileEntry file) {
           return fs.root.createDirectory(
               'directory3')
             .then((DirectoryEntry dir) {
-              return new Future.immediate(new FileAndDir(file, dir));
+              return new Future.value(new FileAndDir(file, dir));
             });
         });
   }
 
   group('directoryReader', () {
     if (FileSystem.supported) {
       test('getFileSystem', getFileSystem);
 
       test('readEntries', () {
         return doDirSetup()
@@ skipping 76 matching lines @@
                 expect(fileObj.name, fileAndDir.file.name);
                 expect(fileObj.relativePath, '');
                 expect(new DateTime.now().difference(
                     fileObj.lastModifiedDate).inSeconds, lessThan(60));
               });
           });
       });
     }
   });
 }