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
{ name: "BoldItalic", fontWeight: 700, italicAngle: 12 },
      ]) {
        const name = `${missing}-${fontInfo.name}`;
        const widths = getXfaFontWidths(name);
        if (!widths) {
          continue;
        }
        const dict = new Dict(null);
        dict.set("BaseFont", Name.get(name));
        dict.set("Type", Name.get("Font"));
        dict.set("Subtype", Name.get("TrueType"));
        dict.set("Encoding", Name.get("WinAnsiEncoding"));
        const descriptor = new Dict(null);
        descriptor.set("Widths", widths);
        dict.set("FontDescriptor", descriptor);
        promises.push(
          partialEvaluator
            .handleSetFont(
              resources,
              [Name.get(name), 1],
               null,
              operatorList,
              task,
              initialState,
               dict,
               {
                fontFamily: missing,
                fontWeight: fontInfo.fontWeight,
                italicAngle: fontInfo.italicAngle,
              }