Follow up with issue: https://github.com/mozilla/pdf.js/issues/14146
Merged pull req: https://github.com/mozilla/pdf.js/pull/14189

Attach (recommended) or Link to PDF file here:
https://bug1708641.bmoattachments.org/attachment.cgi?id=9219459

- This popup appears because JS is enabled;
- And because the pdf contains some unsupported features (e.g. XFA);

Configuration:
- Firefox Nightly & Chrome
- macOS Big Sur 11.6

Steps to reproduce the problem:
1. Run gulp server
2. Open attached pdf

What is the expected behavior? 
No popup on open

What went wrong?
![error](https://user-images.githubusercontent.com/76935202/139354112-707887a2-a6a1-43a9-a92e-45d57c48206a.jpg)



this._unregisterTimeout(oTime);
  }
  endPriv() {
    
  }
  execDialog() {
    
  }
  execMenuItem(item) {
    switch (item) {
      case "SaveAs":
      case "FirstPage":
      case "LastPage":
      case "NextPage":
      case "PrevPage":
      case "ZoomViewIn":
      case "ZoomViewOut":
        this._send({ command: item });
        break;
      case "FitPage":
        this._send({ command: "zoom", value: "page-fit" });
        break;
      case "Print":
        this._send({ command: "print" });
        break;
    }
  }
  getNthPlugInName() {