Change Duration to take proper named optional parameters.

samples/ui_lib/util/DateUtils.dart

Index: samples/ui_lib/util/DateUtils.dart
diff --git a/samples/ui_lib/util/DateUtils.dart b/samples/ui_lib/util/DateUtils.dart
index 6687e61d046d5429b43d001ecd72c0c4cd2f880c..4116d690f9b6742dd568e5af5d412f583498f9cc 100644
--- a/samples/ui_lib/util/DateUtils.dart
+++ b/samples/ui_lib/util/DateUtils.dart
@@ -123,7 +123,11 @@ class DateUtils {
     final now = new Date.now();
     if (datesAreEqual(then, now)) {
       return toHourMinutesString(new Duration(
-          0, then.hour, then.minute, then.second, then.millisecond));
+          days: 0,
+          hours: then.hour,
+          minutes: then.minute,
+          seconds: then.second,
+          milliseconds: then.millisecond));
     }
 
     final today = new Date(now.year, now.month, now.day, 0, 0, 0, 0);