ct().height, 6 * emToPx, epsilon, "mrow");

          element = document.getElementById("core_operator_2");
          assert_approx_equals(element.getBoundingClientRect().height, 6 * emToPx, epsilon, "munder");

          element = document.getElementById("core_operator_3");
          assert_approx_equals(element.getBoundingClientRect().height, 6 * emToPx, epsilon, "mover");

          element = document.getElementById("core_operator_4");
          assert_approx_equals(element.getBoundingClientRect().height