testFindInChildrenFailure() {
    const parentNode = googDom.createElement(TagName.DIV);
    parentNode.innerHTML = '<div>foo</div><b>foo2</b>';

    const index = editorNode.findInChildren(parentNode, (node) => false);
    assertNull('Shouldn\'t find a child', index);
  }
@suppress {strictMissingProperties} suppression added to
                       enable type checking