The prebuilt files include `web/pdf_viewer.js` with some viewer APIs. Those are missing from type declarations.
}),
            ])
          )
          .pipe(gulp.dest(MOZCENTRAL_CONTENT_DIR + "web")),
        gulp
          .src("l10n/en-US/*.properties")
          .pipe(gulp.dest(MOZCENTRAL_L10N_DIR)),
        gulp
          .src(FIREFOX_EXTENSION_DIR + "README.mozilla")
          .pipe(replace(/\bPDFJSSCRIPT_VERSION\b/g, version))
          .pipe(replace(/\bPDFJSSCRIPT_COMMIT\b/g, commit))
          .pipe(gulp.dest(MOZCENTRAL_EXTENSION_DIR)),
        gulp.src("LICENSE").pipe(gulp.dest(MOZCENTRAL_EXTENSION_DIR)),
        gulp
          .src(FIREFOX_CONTENT_DIR + "PdfJsDefaultPreferences.jsm")
          .pipe(transform("utf8", preprocessDefaultPreferences))
          .pipe(gulp.dest(MOZCENTRAL_CONTENT_DIR)),
      ]);
    }
  )
);
gulp.task(
  "chromium",
  gulp.series(
    createBuildNumber,
    "locale",
    function scriptingChromium() {
      const defines = builder.merge(DEFINES, {
        CHROME: true,
        SKIP_BABEL: false,