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.
})
      .pipe(gulp.dest(dir + "web/cmaps")),
    preprocessHTML("web/viewer.html", defines).pipe(gulp.dest(dir + "web")),
    preprocessCSS("web/viewer.css", "generic", defines, true)
      .pipe(postcss([calc(), autoprefixer(AUTOPREFIXER_CONFIG)]))
      .pipe(gulp.dest(dir + "web")),
    gulp
      .src("web/compressed.tracemonkey-pldi-09.pdf")
      .pipe(gulp.dest(dir + "web")),
  ]);
}
gulp.task(
  "generic",
  gulp.series(
    "buildnumber",
    "default_preferences",
    "locale",
    function scripting() {
      var defines = builder.merge(DEFINES, { GENERIC: true });
      return createTemporaryScriptingBundle(defines);
    },
    function () {
      console.log();
      console.log("### Creating generic viewer");
      var defines = builder.merge(DEFINES, { GENERIC: true });
      return buildGeneric(defines, GENERIC_DIR);
    }
  )
);
gulp.task(