Refactor Future constructors.

pkg/scheduled_test/lib/scheduled_server.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.
 
 library scheduled_test.scheduled_server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:io';
 import 'dart:uri';
@@ skipping 73 matching lines @@
         throw e;
       });
     }, "'$description' waiting for $method $path");
   }
 
   /// The handler for incoming [HttpRequest]s to this server. This dispatches
   /// the request to the first handler in the queue. It's that handler's
   /// responsibility to check that the method/path are correct and that it's
   /// being run at the correct time.
   void _handleRequest(HttpRequest request) {
-    wrapFuture(new Future.of(() {
+    wrapFuture(new Future.sync(() {
       if (_handlers.isEmpty) {
         throw "'$description' received ${request.method} ${request.uri.path} "
             "when no more requests were expected.";
       }
       return _handlers.removeFirst().fn(request);
     }).catchError((e) {
       // Close the server so that we don't leave a dangling request.
       _server.then((s) => s.close());
       throw e;
     }), 'receiving ${request.method} ${request.uri}');
   }
 }