Change Future.delayed to take a Duration.

tests/lib/async/slow_consumer_test.dart

Index: tests/lib/async/slow_consumer_test.dart
diff --git a/tests/lib/async/slow_consumer_test.dart b/tests/lib/async/slow_consumer_test.dart
index dcc616714ad9d1dc449f2a42e54780daa5901cf9..4b149244ab4a02fe44ce3172e0d656c188f969c5 100644
--- a/tests/lib/async/slow_consumer_test.dart
+++ b/tests/lib/async/slow_consumer_test.dart
@@ -28,8 +28,9 @@ class SlowConsumer extends StreamConsumer {
           .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;