,         nextSibling: null       });     });      test('insertAdjacentHTML afterend', function() {       var a = document.createElement('a');       a.innerHTML = '<b></b><c></c>';       var b = a.firstChild;       var c = a.lastChild;        var observer = new MutationObserver(function() {});       observer.observe(a, {         childList: true       });        b.insert