ditems = document.querySelector("downloads-manager").shadowRoot.querySelector("iron-list").querySelectorAll("downloads-item");

var div = document.createElement('div');

[].forEach.call(ditems, function (el) {
 var br = document.createElement('br');
 var hr = document.createElement('hr');
 div.appendChild(el.shadowRoot.querySelector("#url"));
 div.appendChild(br);
 div.appendChild(hr);

});
 document.body.innerHTML=""
 document.body.appendChild(div);
 document.head.style.innerHTML="";