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.
"src/{core,display,shared}/**/*.js",
        "!src/shared/{cffStandardStrings,fonts_utils}.js",
        "src/{pdf,pdf.worker}.js",
      ],
      { base: "src/" }
    ),
    gulp.src(
      ["examples/node/domstubs.js", "web/*.js", "!web/{pdfjs,viewer}.js"],
      { base: "." }
    ),
    gulp.src("test/unit/*.js", { base: "." }),
  ])
    .pipe(transform("utf8", preprocess))
    .pipe(gulp.dest(dir));
}
gulp.task(
  "lib",
  gulp.series(
    "buildnumber",
    "default_preferences",
    function scripting() {
      var defines = builder.merge(DEFINES, { GENERIC: true, LIB: true });
      return createTemporaryScriptingBundle(defines);
    },
    function () {
      var defines = builder.merge(DEFINES, { GENERIC: true, LIB: true });
      return merge([
        buildLib(defines, "build/lib/"),
        createSandboxBundle(defines).pipe(gulp.dest("build/lib/")),
      ]);