From 66f064eabf22d58d2827f4e318ef17e89cfe6cb1 Mon Sep 17 00:00:00 2001
From: Hans Muller <hansmuller@chromium.org>
Date: Fri, 24 Jul 2015 15:51:33 -0700
Subject: [PATCH] spring can be null drag must not be

---
 packages/newton/lib/src/scroll_simulation.dart | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/newton/lib/src/scroll_simulation.dart b/packages/newton/lib/src/scroll_simulation.dart
index c71986148a4..9dece962078 100644
--- a/packages/newton/lib/src/scroll_simulation.dart
+++ b/packages/newton/lib/src/scroll_simulation.dart
@@ -18,12 +18,11 @@ class ScrollSimulation extends SimulationGroup {
   double _offset = 0.0;
 
   ScrollSimulation(double position, double velocity, double leading,
-      double trailing, [SpringDescription spring, double drag])
+      double trailing, SpringDescription spring, double drag)
       : _leadingExtent = leading,
         _trailingExtent = trailing,
         _springDesc = spring,
         _drag = drag {
-    assert((spring != null && drag != null) || (spring == null && drag == null));
     _chooseSimulation(position, velocity, 0.0);
   }