querySelector('x-project');
  var child = document.createElement('p');
  child.innerHTML = "hello";
  // child will be inserted into p after distributeContent is performed.
  re.appendChild(child);
  flush();
  child.addEventListener('child-event', function(e){
    var path = e.composedPath();
    assert.isTrue(path.indexOf(p) !== -1, 'path contains p');
    assert.isTrue(path.indexOf(re) !== -1, 'path contains re');
    done();
  });
  var evt = new CustomEvent('child-event');
  child.dispatchEvent(evt);
 