;
    const observer = new PerformanceObserver(
      t.step_func_done(function(entryList) {
        assert_equals(entryList.getEntries().length, 1);
        const entry = entryList.getEntries()[0];
        assert_equals(entry.entryType, 'largest-contentful-paint');
        assert_greater_than_equal(entry.renderTime, beforeRender);
        assert_greater_than_equal(performance.now(), entry.renderTime);
        assert_approx_equals(entry.startTime, entry.renderTime, 0.001,
          'startTime should be equa