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
if (
      this.pdfManager.enableXfa &&
      this.formInfo.hasXfa &&
      !this.formInfo.hasAcroForm
    ) {
      const data = this.xfaData;
      return shadow(this, "xfaFactory", data ? new XFAFactory(data) : null);
    }
    return shadow(this, "xfaFaxtory", null);
  }
  get isPureXfa() {
    return this.xfaFactory && this.xfaFactory.isValid();
  }
  get htmlForXfa() {