Attach (recommended) or Link to PDF file here:
http://help.adobe.com/en_US/livecycle/11.0/SampleForms/941/Form.pdf

- Web browser and its version: Firefox 89.0.1
- Operating system and its version: Windows 10 10.0.19043.1052
- PDF.js version: commit bdfcdd6f8326f22c135edfa29a341ea4c558f3d1
- Is a browser extension: No

Steps to reproduce the problem:
1. Enable XFA support
2. Open form

What is the expected behavior? (add screenshot)
Page 3 (of 4) renders
![image](https://user-images.githubusercontent.com/7104454/122686842-622e9980-d1e1-11eb-92ab-86fe488560f2.png)

What went wrong? (add screenshot)
Only 3 pages total render in pdf.js
const acroForm = this.catalog.acroForm;
    if (!acroForm) {
      return null;
    }
    const xfa = acroForm.get("XFA");
    const entries = {
      "xdp:xdp": "",
      template: "",
      datasets: "",
      config: "",
      connectionSet: "",
      localeSet: "",
      stylesheet: "",
      "/xdp:xdp": "",
    };
    if (isStream(xfa) && !xfa.isEmpty) {
      try {
        entries["xdp:xdp"] = stringToUTF8String(xfa.getString());
        return entries;
      } catch (_) {
        warn("XFA - Invalid utf-8 string.");
        return null;
      }