STR:
  - Go to https://mozilla.github.io/pdf.js/web/viewer.html
  - Click on "Open File" and open a pdf

The `Download` button and the `Current view` one just disappear.
I can reproduce this bug with Firefox nightly, Chrome stable and Epiphany on debian.
return this.externalServices.supportsIntegratedFind;
  },
  get supportsDocumentFonts() {
    return this.externalServices.supportsDocumentFonts;
  },
  get loadingBar() {
    const bar = new ProgressBar("#loadingBar");
    return shadow(this, "loadingBar", bar);
  },
  get supportedMouseWheelZoomModifierKeys() {
    return this.externalServices.supportedMouseWheelZoomModifierKeys;
  },
  initPassiveLoading() {
    if (
      typeof PDFJSDev === "undefined" ||
      !PDFJSDev.test("MOZCENTRAL || CHROME")
    ) {
      throw new Error("Not implemented: initPassiveLoading");
    }
    this.externalServices.initPassiveLoading({
      onOpenWithTransport: (url, length, transport) => {
        this.open(url, { length, range: transport });
      },
      onOpenWithData: (data, contentDispositionFilename) => {
        if (isPdfFile(contentDispositionFilename)) {
          this._contentDispositionFilename = contentDispositionFilename;
        }
        this.open(data);
      },
      onOpenWithURL: (url, length, originalUrl) => {