fix bug

Runtime/material/app.cs

                     onGenerateRoute: this.widget.onGenerateRoute,
                     onUnknownRoute: this.widget.onUnknownRoute,
                     builder: this.widget.builder,
-                    window: this.widget.window,
                     textStyle: AppUtils._errorTextStyle
                 )
             );

Samples/UIWidgetSample/MaterialSample.cs

 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.material;
 using Unity.UIWidgets.painting;
-using Unity.UIWidgets.ui;
 using Unity.UIWidgets.widgets;
 using UnityEngine;
 using Color = Unity.UIWidgets.ui.Color;
         };
 
         protected override Widget createWidget() {
-            return new WidgetsApp(
-                home: this.testCases[this.testCaseId],
-                pageRouteBuilder: this.pageRouteBuilder);
+            return new MaterialApp(
+                home: this.testCases[this.testCaseId]);
         }
     }