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)


case "dashDot":
          style.style = "dashed";
          break;
        case "dashDotDot":
          style.style = "dashed";
          break;
        case "dashed":
          style.style = "dashed";
          break;
        case "dotted":
          style.style = "dotted";
          break;
        case "embossed":
          style.style = "ridge";
          break;
        case "etched":
          style.style = "groove";
          break;
        case "lowered":
          style.style = "inset";
          break;
        case "raised":
          style.style = "outset";
          break;
      }
    }
    return style;
  }
}
class Encoding extends OptionObject {