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

samples/swarm/swarm_ui_lib/layout/GridLayout.dart

Index: samples/swarm/swarm_ui_lib/layout/GridLayout.dart
diff --git a/samples/swarm/swarm_ui_lib/layout/GridLayout.dart b/samples/swarm/swarm_ui_lib/layout/GridLayout.dart
index 10526205733be992aa8ad54b6e2cf2c1cdf0b145..5fe1a7edbbdcf22ee6a08493ef03036dd57dc12d 100644
--- a/samples/swarm/swarm_ui_lib/layout/GridLayout.dart
+++ b/samples/swarm/swarm_ui_lib/layout/GridLayout.dart
@@ -232,10 +232,10 @@ class GridLayout extends ViewLayout {
       int startEdge = tracks[i].start;
       int endEdge;
       if (i < tracks.length - 1) {
-        endEdge = tracks[i + 1].start.round().toInt();
+        endEdge = tracks[i + 1].start.round();
         tracks[i + 1].start = endEdge;
       } else {
-        endEdge = finalPosition.round().toInt();
+        endEdge = finalPosition.round();
       }
       int breadth = endEdge - startEdge;