);        var records = observer.takeRecords();       assert.equal(records.length, 0);       expectMutationRecord(records[0], {         type: 'childList',         target: div,         addedNodes: makeNodeList(b, c, d),         removedNodes: makeNodeList(),         previousSibling: a,         nextSibling: null       });     });      test('Append multiple at once at the 