Add polyfills for modern html

polyfill.html

<script>
  if (typeof Promise == "undefined") {
    document.write('<script src="https://cdn.jsdelivr.net/npm/promise-polyfill@8.1.0/dist/polyfill.min.js"><\/script>');
  }
  if (window.URL && window.URL.prototype && ('href' in window.URL.prototype)) {
  } else {
    document.write('<script src="https://cdn.jsdelivr.net/gh/arv/DOM-URL-Polyfill@e54d67f/src/url.min.js"><\/script>');
  }
  if (typeof URLSearchParams == "undefined") {
    document.write('<script src="https://cdn.jsdelivr.net/npm/@ungap/url-search-params@0.1.2/min.js"><\/script>');
  }
  if (typeof fetch == "undefined") {
    document.write('<script src="https://cdn.jsdelivr.net/npm/whatwg-fetch@3.0.0/dist/fetch.umd.min.js"><\/script>');
  }
</script>