The prebuilt files include `web/pdf_viewer.js` with some viewer APIs. Those are missing from type declarations.
return merge([
    createMainBundle(defines).pipe(gulp.dest(dir + "build")),
    createWorkerBundle(defines).pipe(gulp.dest(dir + "build")),
    createSandboxBundle(defines).pipe(gulp.dest(dir + "build")),
    createWebBundle(defines, {
      defaultPreferencesDir: defines.SKIP_BABEL
        ? "minified/"
        : "minified-legacy/",
    }).pipe(gulp.dest(dir + "web")),
    createImageDecodersBundle(
      builder.merge(defines, { IMAGE_DECODERS: true })
    ).pipe(gulp.dest(dir + "image_decoders")),
    gulp.src(COMMON_WEB_FILES, { base: "web/" }).pipe(gulp.dest(dir + "web")),
    gulp
      .src(["web/locale/*/viewer.properties", "web/locale/locale.properties"], {
        base: "web/",
      })
      .pipe(gulp.dest(dir + "web")),
    createCMapBundle().pipe(gulp.dest(dir + "web/cmaps")),
    createStandardFontBundle().pipe(gulp.dest(dir + "web/standard_fonts")),
    preprocessHTML("web/viewer.html", defines).pipe(gulp.dest(dir + "web")),
    preprocessCSS("web/viewer.css", "minified", 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")),
  ]);
}
async function parseMinified(dir) {