[Cupertino] Fix bug

Runtime/widgets/heroes.cs

             HeroFlightShuttleBuilder shuttleBuilder,
             bool isUserGestureTransition
         ) {
-            D.assert(fromHero.widget.tag == toHero.widget.tag);
+            D.assert(fromHero.widget.tag.ToString() == toHero.widget.tag.ToString());
             this.type = type;
             this.overlay = overlay;
             this.navigatorRect = navigatorRect;

Samples/UIWidgetsGallery/demo/cupertino/cupertino_navigation_demo.cs

     class Tab1ItemPageState : State<Tab1ItemPage> {
         public override void initState() {
             base.initState();
-            this.relatedColors = new List<Color>(10);
 
             this.relatedColors = new List<Color>();
             for (int i = 0; i < 10; i++) {