 'lastChild incorrect');
    assert.equal(element.nextSibling, null, 'nextSibling incorrect');
    assert.equal(element.previousSibling, null, 'previousSibling incorrect');
    assert.equal(element.firstElementChild, null, 'firstElementChild incorrect');
    assert.equal(element.lastElementChild, null, 'lastElementChild incorrect');
    assert.equal(element.nextElementSibling, null, 'nextElementSibling incorrect');
    assert.equal(element.previousElementSibling, null, 'previousElementSibling incorrect');
 