parseNav(navHtml) {
    var navElement = Object(core["querySelectorByType"])(navHtml, "nav", "page-list");
    var navItems = navElement ? Object(core["qsa"])(navElement, "li") : [];
    var length = navItems.length;
    var i;
    var list = [];
    var item;
    if (!navItems || length === 0) return list;

    for (i = 0; i < length; ++i) {
      item = this.item(navItems[i]);
      list.push(item);
    }

    return list;
  }
Parse a Nav PageList
@private
@param  {node} navHtml
@return {PageList.item[]} list