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.
gulp.task(
  "image_decoders",
  gulp.series("buildnumber", function () {
    console.log();
    console.log("### Creating image decoders");
    var defines = builder.merge(DEFINES, {
      GENERIC: true,
      IMAGE_DECODERS: true,
    });
    return createImageDecodersBundle(defines).pipe(
      gulp.dest(IMAGE_DECODERS_DIR)
    );
  })
);
gulp.task(
  "image_decoders-legacy",
  gulp.series("buildnumber", function () {
    console.log();
    console.log("### Creating (legacy) image decoders");
    var defines = builder.merge(DEFINES, {
      GENERIC: true,
      IMAGE_DECODERS: true,
      SKIP_BABEL: false,
    });
    return createImageDecodersBundle(defines).pipe(
      gulp.dest(IMAGE_DECODERS_LEGACY_DIR)
    );
  })
);
function buildMinified(defines, dir) {