fix navigation bug

com.unity.uiwidgets/Runtime/widgets/focus_manager.cs

             get { return FocusManager.instance.highlightMode; }
         }
 
-        public FocusScopeNode nearestScope {
+        public virtual FocusScopeNode nearestScope {
             get { return enclosingScope; }
         }
 
             skipTraversal: skipTraversal
         ) {}
 
-        public FocusScopeNode nearestScope {
+        public override FocusScopeNode nearestScope {
             get { return this; }
         }