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)


attributes.style.display = "flex";
        attributes.style.flexDirection = "column";
        switch (this.para.vAlign) {
          case "top":
            attributes.style.justifyContent = "start";
            break;
          case "bottom":
            attributes.style.justifyContent = "end";
            break;
          case "middle":
            attributes.style.justifyContent = "center";
            break;
        }
        const paraStyle = this.para[$toStyle]();
        if (!value.attributes.style) {
          value.attributes.style = paraStyle;
        } else {
          for (const [key, val] of Object.entries(paraStyle)) {
            if (!(key in value.attributes.style)) {
              value.attributes.style[key] = val;
            }
          }
        }
      }
    }
    return HTMLResult.success(createWrapper(this, html), bbox);
  }
}
class Edge extends XFAObject {