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)


"radix",
      "right",
    ]);
    this.id = attributes.id || "";
    this.locale = attributes.locale || "";
    this.maxH = getMeasurement(attributes.maxH, "0pt");
    this.maxW = getMeasurement(attributes.maxW, "0pt");
    this.minH = getMeasurement(attributes.minH, "0pt");
    this.minW = getMeasurement(attributes.minW, "0pt");
    this.name = attributes.name || "";
    this.presence = getStringOption(attributes.presence, [
      "visible",
      "hidden",
      "inactive",
      "invisible",
    ]);
    this.relevant = getRelevant(attributes.relevant);
    this.rotate = getInteger({
      data: attributes.rotate,
      defaultValue: 0,
      validate: x => x % 90 === 0,
    });
    this.use = attributes.use || "";
    this.usehref = attributes.usehref || "";
    this.w = attributes.w ? getMeasurement(attributes.w) : "";
    this.x = getMeasurement(attributes.x, "0pt");
    this.y = getMeasurement(attributes.y, "0pt");
    this.assist = null;
    this.border = null;
    this.caption = null;