Fix shrine null reference issue.

Runtime/widgets/navigator.cs

             get { return false; }
         }
 
-        public object currentResult {
+        public virtual object currentResult {
             get { return null; }
         }
 

Samples/UIWidgetsGallery/demo/shrine/shrine_order.cs

 
         public Order order;
 
-        public new Order currentResult {
+        public override object currentResult {
             get { return this.order; }
         }