anchor.diff:  /// (when called from JS).
   @JS()
   @anonymous
  +@staticInterop
   abstract class InitializeEngineFnParameters {
   }
   
  
positive.code: /// and run a Flutter Web app, from JavaScript.
  @JS()
  @anonymous
  abstract class FlutterEngineInitializer{
    external factory FlutterEngineInitializer({
      required InitializeEngineFn initializeEngine,
  
negative.code: /// runApp function of the FlutterAppRunner object (from JS).
  @JS()
  @anonymous
  @staticInterop
  abstract class RunAppFnParameters {
  }
  
  