Remove Futures class, move methods to Future.

tests/standalone/io/http_session_test.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.
 
 import 'dart:async';
 import 'dart:io';
 
 const SESSION_ID = "DARTSESSID";
 
 String getSessionId(List<Cookie> cookies) {
@@ skipping 43 matching lines @@
     futures.add(connectGetSession(server.port).then((session) {
       Expect.isNotNull(session);
       Expect.isTrue(sessions.contains(session));
       return connectGetSession(server.port, session).then((session2) {
         Expect.equals(session2, session);
         Expect.isTrue(sessions.contains(session2));
         return session2;
         });
     }));
   }
-  Futures.wait(futures).then((clientSessions) {
+  Future.wait(futures).then((clientSessions) {
     Expect.equals(sessions.length, sessionCount);
     Expect.setEquals(new Set.from(clientSessions), sessions);
     server.close();
   });
 }
 
 void testTimeout(int sessionCount) {
   HttpServer server = new HttpServer();
   server.sessionTimeout = 0;
   server.listen("127.0.0.1", 0);
   var timeouts = [];
   server.defaultRequestHandler = (request, response) {
     var c = new Completer();
     timeouts.add(c.future);
     request.session().onTimeout = () {
       c.complete(null);
     };
     response.outputStream.close();
   };
 
   var futures = [];
   for (int i = 0; i < sessionCount; i++) {
     futures.add(connectGetSession(server.port));
   }
-  Futures.wait(futures).then((clientSessions) {
-    Futures.wait(timeouts).then((_) {
+  Future.wait(futures).then((clientSessions) {
+    Future.wait(timeouts).then((_) {
       futures = [];
       for (var id in clientSessions) {
         futures.add(connectGetSession(server.port, id).then((session) {
           Expect.isNotNull(session);
           Expect.notEquals(id, session);
         }));
       }
-      Futures.wait(futures).then((_) {
+      Future.wait(futures).then((_) {
         server.close();
       });
     });
   });
 }
 
 void main() {
   testSessions(5);
   testTimeout(5);
 }