Change Future.delayed to take a Duration.

tests/lib/async/slow_consumer_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.
 
 // VMOptions=--old_gen_heap_size=32
 
 library slow_consumer_test;
 
 import 'dart:async';
 import 'dart:isolate';
@@ skipping 10 matching lines @@
 
   Future consume(Stream stream) {
     Completer completer = new Completer();
     var subscription;
     subscription = stream.listen(
       (List<int> data) {
         current = current
           .then((count) {
             // Simulated amount of time it takes to handle the data.
             int ms = data.length * 1000 ~/ bytesPerSecond;
+            Duration duration = new Duration(milliseconds: ms);
             subscription.pause();
-            return new Future.delayed(ms, () {
+            return new Future.delayed(duration, () {
               subscription.resume();
               // Make sure we use data here to keep tracking it.
               return count + data.length;
             });
           });
         },
       onDone: () { current.then((count) { completer.complete(count); }); });
     return completer.future;
   }
 }
@@ skipping 47 matching lines @@
   // file). If the consumer doesn't pause the data-provider it will run out of
   // heap-space.
 
   new DataProvider(800 * MB, 100 * MB, 1 * MB).stream
     .pipe(new SlowConsumer(200 * MB))
     .then((count) {
       port.close();
       Expect.equals(100 * MB, count);
     });
 }