Ignore analyzer implict dynamic checks for js_util generic return type (flutter#92271)

Author: rileyporter

dev/benchmarks/macrobenchmarks/lib/src/web/bench_text_layout.dart

@@ -75,6 +75,7 @@ void _setTestMode(_TestMode? mode) {
       // Keep as null.
       break;
   }
+  // ignore: implicit_dynamic_function
   js_util.callMethod(
     html.window,
     '_flutter_internal_update_experiment',

dev/integration_tests/web_e2e_tests/test_driver/text_editing_integration.dart

@@ -237,12 +237,14 @@ void main() {
 
 KeyboardEvent dispatchKeyboardEvent(
     EventTarget target, String type, Map<String, dynamic> args) {
+  // ignore: implicit_dynamic_function
   final Object jsKeyboardEvent = js_util.getProperty(window, 'KeyboardEvent') as Object;
   final List<dynamic> eventArgs = <dynamic>[
     type,
     args,
   ];
 
+  // ignore: implicit_dynamic_function
   final KeyboardEvent event = js_util.callConstructor(
           jsKeyboardEvent, js_util.jsify(eventArgs) as List<dynamic>)
       as KeyboardEvent;