fix some tests

Author: mdebbar

lib/web_ui/test/engine/surface/surface_test.dart

@@ -16,7 +16,7 @@ void main() {
 void testMain() {
   group('Surface', () {
     setUpAll(() async {
-      await bootstrapAndRunApp();
+      await bootstrapAndRunApp(withImplicitView: true);
     });
 
     setUp(() {

lib/web_ui/test/html/compositing/backdrop_filter_golden_test.dart

@@ -17,6 +17,7 @@ void main() {
 
 Future<void> testMain() async {
   setUpUnitTests(
+    withImplicitView: true,
     emulateTesterEnvironment: false,
     setUpTestViewDimensions: false,
   );