Make ~/, round, ceil, floor, truncate return ints. Remove toInt.

samples/swarm/swarm_ui_lib/view/ConveyorView.dart

Index: samples/swarm/swarm_ui_lib/view/ConveyorView.dart
diff --git a/samples/swarm/swarm_ui_lib/view/ConveyorView.dart b/samples/swarm/swarm_ui_lib/view/ConveyorView.dart
index 696c1bd4d74c3ad3c843f3c33b93e31e9bbedcad..420209f901b998029bda1706c58a0b1d9660180f 100644
--- a/samples/swarm/swarm_ui_lib/view/ConveyorView.dart
+++ b/samples/swarm/swarm_ui_lib/view/ConveyorView.dart
@@ -67,7 +67,7 @@ class ConveyorView extends CompositeView {
 
     if (animate) {
       animationTimeoutId = window.setTimeout(
-          () { _onAnimationEnd(); }, (durationSeconds * 1000).toInt());
+          () { _onAnimationEnd(); }, (durationSeconds * 1000).truncate());
     }
     // TODO(mattsh), we should set the visibility to hide everything but the
     // selected view.