      }));
      observer.observe({ entryTypes: ['longtask'], buffered: false });
      const containerObject = document.createElement(container.name);
      containerObject.id = container.name + '-id';
      containerObject.name = container.name + '-name';
      containerObject[container.src] = 'resources/subframe-with-longtask.html';
      document.body.appendChild(containerObject);
    });
    const timeout = new Promise(
      (resolve, reject) => t.step_timeout(
        () => { reject(new Error('observ