http://webintents.org/save image/* as URL client

gistfile1.js

var i = new Intent({
  "action": "http://webintents.org/save",
  "type": "image/*",
  "extras": { "url": "http://placekitten.com/g/200/300" }
})

var onsuccess = function(data) {
  var img1 = document.getElementById("img1");
  if(data instanceof Blob) {
    img1.src = URL.createObjectURL(data);
  }
  else {
    img1.src = data;
  }
};

var onerror = function(){ };
window.navigator.startActivity(i, onsuccess, onerror);