Refactor Future constructors.

tests/standalone/io/http_proxy_test.dart

 // Copyright (c) 2013, 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.
 
 import "package:expect/expect.dart";
 import "dart:async";
 import 'dart:crypto';
 import "dart:io";
 import "dart:uri";
 import 'dart:utf';
@@ skipping 476 matching lines @@
       client.findProxy = (Uri uri) {
         return "PROXY localhost:${proxyServer.port}";
       };
 
       client.authenticateProxy = (host, port, scheme, realm) {
         client.addProxyCredentials(
             "localhost",
             proxyServer.port,
             "realm",
             new HttpClientBasicCredentials("test", "test"));
-        return new Future.immediate(true);
+        return new Future.value(true);
       };
 
       for (int i = 0; i < loopCount; i++) {
         test(bool secure) {
           String url = secure
               ? "https://localhost:${secureServer.port}/A"
               : "http://127.0.0.1:${server.port}/A";
 
           client.postUrl(Uri.parse(url))
             .then((HttpClientRequest clientRequest) {
@@ skipping 119 matching lines @@
   testDirectProxy();
   testProxy();
   testProxyChain();
   testProxyFromEnviroment();
   testProxyAuthenticate();
   // This test is not normally run. It can be used for locally testing
   // with a real proxy server (e.g. Apache).
   //testRealProxy();
   //testRealProxyAuth();
 }