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.
var GENERIC_DIR = BUILD_DIR + "generic/";
var GENERIC_LEGACY_DIR = BUILD_DIR + "generic-legacy/";
var COMPONENTS_DIR = BUILD_DIR + "components/";
var COMPONENTS_LEGACY_DIR = BUILD_DIR + "components-legacy/";
var IMAGE_DECODERS_DIR = BUILD_DIR + "image_decoders/";
var IMAGE_DECODERS_LEGACY_DIR = BUILD_DIR + "image_decoders-legacy/";
var DEFAULT_PREFERENCES_DIR = BUILD_DIR + "default_preferences/";
var MINIFIED_DIR = BUILD_DIR + "minified/";
var MINIFIED_LEGACY_DIR = BUILD_DIR + "minified-legacy/";
var JSDOC_BUILD_DIR = BUILD_DIR + "jsdoc/";
var GH_PAGES_DIR = BUILD_DIR + "gh-pages/";
var SRC_DIR = "src/";
var LIB_DIR = BUILD_DIR + "lib/";
var DIST_DIR = BUILD_DIR + "dist/";
var TYPES_DIR = BUILD_DIR + "types/";
const TMP_DIR = BUILD_DIR + "tmp/";
var TYPESTEST_DIR = BUILD_DIR + "typestest/";
var COMMON_WEB_FILES = ["web/images/*.{png,svg,gif,cur}", "web/debugger.js"];
var MOZCENTRAL_DIFF_FILE = "mozcentral.diff";
var REPO = "git@github.com:mozilla/pdf.js.git";
var DIST_REPO_URL = "https://github.com/mozilla/pdfjs-dist";
var builder = require("./external/builder/builder.js");
var CONFIG_FILE = "pdfjs.config";
var config = JSON.parse(fs.readFileSync(CONFIG_FILE).toString());
var AUTOPREFIXER_CONFIG = {
  overrideBrowserslist: [
    "last 2 versions",
    "Chrome >= 49", 
    "Firefox >= 52", 
    "Firefox ESR",