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
HelveticaItalicLineHeight,
  HelveticaRegularFactors,
  HelveticaRegularLineHeight,
} from "./helvetica_factors.js";
import {
  LiberationSansBoldItalicWidths,
  LiberationSansBoldWidths,
  LiberationSansItalicWidths,
  LiberationSansRegularWidths,
} from "./liberationsans_widths.js";
import {
  MyriadProBoldFactors,
  MyriadProBoldItalicFactors,
  MyriadProBoldItalicLineHeight,
  MyriadProBoldLineHeight,
  MyriadProItalicFactors,
  MyriadProItalicLineHeight,
  MyriadProRegularFactors,
  MyriadProRegularLineHeight,
} from "./myriadpro_factors.js";
import {
  SegoeuiBoldFactors,
  SegoeuiBoldItalicFactors,
  SegoeuiBoldItalicLineHeight,
  SegoeuiBoldLineHeight,
  SegoeuiItalicFactors,
  SegoeuiItalicLineHeight,
  SegoeuiRegularFactors,
  SegoeuiRegularLineHeight,
} from "./segoeui_factors.js";