Stop gif animations in Chrome with escape

It occurred to me that one of the basic browser features still missing in Chrome, to turn off gif animations as you hit the escape key, ought to be implementable as a tiny user script through canvas:

document.addEventListener('keydown', freeze_gifs_on_escape, true);

function freeze_gifs_on_escape(e) {
  if (e.keyCode == 27 && !e.shiftKey && !e.ctrlKey && !e.altKey && !e.metaKey) {
    [].slice.apply(document.images).filter(is_gif_image).map(freeze_gif);
  }
}

function is_gif_image(i) {
  return /^(?!data:).*\.gif/i.test(i.src);
}

function freeze_gif(i) {
  var c = document.createElement('canvas');
  var w = c.width = i.width;
  var h = c.height = i.height;
  c.getContext('2d').drawImage(i, 0, 0, w, h);
  try {
    i.src = c.toDataURL("image/gif"); // if possible, retain all css aspects
  } catch(e) { // cross-domain -- mimic original with all its tag attributes
    for (var j = 0, a; a = i.attributes[j]; j++)
      c.setAttribute(a.name, a.value);
    i.parentNode.replaceChild(c, i);
  }
}

It mostly works, though for gif images loaded from another domain, we're unfortunately still out of luck. I hope Chrome will soon offer an extension flag for doing privileged canvas operations, such as drawImage, for an image loaded from another domain, like here.

That privilege could even involve a manual extension review process in the Chrome extension gallery, for all I care; it is jarring that we can't fix user experience bugs like this due to the enforced security model.

Edit: As suggested in the tip below, we don't really need to .toDataURL the image, although that gives the best results on pages that apply css styling to img tags that we won't inherit to the canvas tag. The script has been updated to work everywhere; direct install link here.