als(attribution.entryType, 'taskattribution');
          assert_equals(attribution.name, 'unknown');
          assert_equals(attribution.duration, 0);
          assert_equals(attribution.startTime, 0);
          assert_equals(attribution.containerId, container.name + '-id');
          assert_equals(attribution.containerName, container.name + '-name');
          assert_equals(attribution.containerSrc, 'resources/subframe-with-longtask.html');
          observer.disconnect();
          resolve();
        });
