update app.cs

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

             return Future.value(true).to<bool>();
         }
 
+        public void didChangeAccessibilityFeatures() {
+           
+        }
+
         Route<object> _onUnknownRoute(RouteSettings settings) {
             D.assert(() => {
                 if (widget.onUnknownRoute == null) {