simple javascript code to save the page as an image, using http://html2canvas.hertzen.com/ , no external script required (, designed to run from scratchpad/console)

save_page_as_image.js

var script = document.createElement('script');
script.onload = function () {
  html2canvas(document.body, {
    allowTaint: true,
    //taintTest: false,
    logging: true,
    onrendered: function(canvas) {
      var img = canvas.toDataURL("image/png"); // window.location.href = img.replace("image/png", "image/octet-stream");
      var link = document.createElement("a");
      link.download = "page.png";
      link.href = img;
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
      delete link;
    }
  });
};
script.src = "//html2canvas.hertzen.com/build/html2canvas.js";
document.head.appendChild(script);