akeShadowRootWithSlot(d);
          var recorded = [];
          function handler(info) {
            recorded = info;
          }
          var observer = ShadyDOM.observeChildren(d, handler);
          var child1 = document.createElement('div');
          ShadyDOM.wrapIfNeeded(d).appendChild(child1);
          handler(observer.takeRecords());
          assert.equal(recorded[0].addedNodes.length, 1);
          assert.equal(recorded[0].addedNodes[0], child1);
          recorded = [];
          var child2 = 