reventDefault();
  i.contentWindow.navigation.onnavigate = t.unreached_func("navigate event should not fire in the iframe, because the traversal was cancelled in the top window");
  await assertBothRejectDOM(t, navigation.traverseTo(navigation.entries()[start_index].key), "AbortError");
  assert_equals(navigation.currentEntry.index, start_index + 1);
  assert_equals(i.contentWindow.navigation.currentEntry.index, 1);
}, "navigation.traverseTo() - if a top window cancels the traversal, any iframes should not 