       });     });      test('insertBefore removal document fragment', function() {       var df = document.createDocumentFragment();       var a = df.appendChild(document.createElement('a'));       var b = df.appendChild(document.createElement('b'));       var c = df.appendChild(document.createElement('c'));        var d = document.createElement('d');       var e = d.appendChild(document.createElement('e'));       var f = 