Attach (recommended) or Link to PDF file here:
[FormDB2_fr.pdf](https://github.com/mozilla/pdf.js/files/7352426/FormDB2_fr.pdf)

Configuration:
- Web browser and its version: Firefox nightly
- Operating system and its version: linux debian

Steps to reproduce the problem:
1. Open the pdf
2. The image on the top of each pages is missing 

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/137465500-e8788893-f33d-4532-871d-43b464fa85f4.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/137465363-f2b35fe4-6776-45e9-b9e4-ccef6d9ad670.png)

width: this.medium.long,
          height: this.medium.short,
        };
      }
    } else {
      warn("XFA - No medium specified in pageArea: please file a bug.");
    }
    this[$childrenToHTML]({
      filter: new Set(["area", "draw", "field", "subform"]),
      include: true,
    });
    
    
    this[$childrenToHTML]({
      filter: new Set(["contentArea"]),
      include: true,
    });
    return HTMLResult.success({
      name: "div",
      children,
      attributes: {
        class: ["xfaPage"],
        id: this[$uid],
        style,
        xfaName: this.name,
      },
    });
  }
}
class PageSet extends XFAObject {