e list of available
  // images, as opposed to just complete images, this would allow lazyload
  // images (in addition to non-lazyload ones) to coalesce with these in-flight
  // entries in the list of available images too. In that case we'd need to test
  // for this here.
  // [1]: https://html.spec.whatwg.org/multipage/images.html#updating-the-image-data
  const lazyload_image_promise = new Promise((resolve, reject) => {
    const img = new Image();
    img.loading = 'lazy';
    img.onload = resolve;
  