On https://github.com/mozilla/pdf.js/wiki/Required-Browser-Features we mention required browser features for PDF.js, but I have the feeling that not all of them are necessary nowadays since we moved to using more modern features over the years. Moreover, as indicated in https://github.com/mozilla/pdf.js/issues/11950#issuecomment-637149085, some features may be missing such as range requests or `async/await`.

In short, we should verify which are still necessary and update the wiki page and the automated feature detection if possible.
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  var DIST_DESCRIPTION = "Generic build of Mozilla's PDF.js library.";
  var DIST_KEYWORDS = ["Mozilla", "pdf", "pdf.js"];
  var DIST_HOMEPAGE = "http://mozilla.github.io/pdf.js/";
  var DIST_BUGS_URL = "https://github.com/mozilla/pdf.js/issues";
  var DIST_LICENSE = "Apache-2.0";
  var npmManifest = {
    name: DIST_NAME,
    version: VERSION,
    main: "build/pdf.js",
    types: "types/pdf.d.ts",
    description: DIST_DESCRIPTION,
    keywords: DIST_KEYWORDS,