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)


}
    if (!ui.attributes.class) {
      ui.attributes.class = [];
    }
    switch (this.caption.placement) {
      case "left":
        ui.children.splice(0, 0, caption);
        ui.attributes.class.push("xfaLeft");
        break;
      case "right":
        ui.children.push(caption);
        ui.attributes.class.push("xfaLeft");
        break;
      case "top":
        ui.children.splice(0, 0, caption);
        ui.attributes.class.push("xfaTop");
        break;
      case "bottom":
        ui.children.push(caption);
        ui.attributes.class.push("xfaTop");
        break;
      case "inline":
        
        ui.attributes.class.push("xfaLeft");
        break;
    }
    return HTMLResult.success(createWrapper(this, html), bbox);
  }
}
class Fill extends XFAObject {