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
let obj = this.pageDict.get("UserUnit");
    if (!isNum(obj) || obj <= 0) {
      obj = DEFAULT_USER_UNIT;
    }
    return shadow(this, "userUnit", obj);
  }
  get view() {
    
    
    
    
    const { cropBox, mediaBox } = this;
    let view;
    if (cropBox === mediaBox || isArrayEqual(cropBox, mediaBox)) {
      view = mediaBox;
    } else {
      const box = Util.intersect(cropBox, mediaBox);
      if (box && box[2] - box[0] !== 0 && box[3] - box[1] !== 0) {
        view = box;
      } else {
        warn("Empty /CropBox and /MediaBox intersection.");
      }
    }
    return shadow(this, "view", view || mediaBox);
  }
  get rotate() {