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 (parseFloat(cssFontInfo.fontWeight) >= 700) {
        property = "bolditalic";
      } else {
        property = "italic";
      }
    } else if (parseFloat(cssFontInfo.fontWeight) >= 700) {
      property = "bold";
    }
    if (!property) {
      if (
        pdfFont.name.includes("Bold") ||
        (pdfFont.psName && pdfFont.psName.includes("Bold"))
      ) {
        property = "bold";
      }
      if (
        pdfFont.name.includes("Italic") ||
        pdfFont.name.endsWith("It") ||
        (pdfFont.psName &&
          (pdfFont.psName.includes("Italic") || pdfFont.psName.endsWith("It")))
      ) {
        property += "italic";
      }
    }
    if (!property) {
      property = "regular";
    }
    font[property] = pdfFont;
  }
  getDefault() {