Attach (recommended) or Link to PDF file here:
https://guichet.public.lu/dam-assets/catalogue-formulaires/tva/tva-option-aic-pers-morales/tva-option-aic-pers-morale-DE.pdf

Configuration:
- Web browser and its version: Firefox Nightly 91.0a1 (2021-06-26) (64-bit)
- Operating system and its version: Windows 10.0.19043.1052
- PDF.js version: N/A

Steps to reproduce the problem:
1. enableXFA in Firefox Nightly
2. Open form

What is the expected behavior? (add screenshot)
Header image is scaled properly
![image](https://user-images.githubusercontent.com/7104454/123525954-905d1f00-d6a2-11eb-840e-be30eee395e1.png)

What went wrong? (add screenshot)
Image is scaled to fit
![image](https://user-images.githubusercontent.com/7104454/123525957-96530000-d6a2-11eb-9991-bf7f37c6f1a5.png)


} else {
      type = "checkbox";
      className = "xfaCheckbox";
      dataId = field[$data] && field[$data][$uid];
    }
    const input = {
      name: "input",
      attributes: {
        class: [className],
        style,
        fieldId,
        dataId,
        type,
        checked,
        xfaOn: exportedValue.on,
      },
    };
    if (groupId) {
      input.attributes.name = groupId;
    }
    return HTMLResult.success({
      name: "label",
      attributes: {
        class: ["xfaLabel"],
      },
      children: [input],
    });
  }
}
class ChoiceList extends XFAObject {