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)


"rest",
    ]);
    this.relevant = getRelevant(attributes.relevant);
    this.use = attributes.use || "";
    this.usehref = attributes.usehref || "";
    this.desc = null;
    this.extras = null;
    this.medium = null;
    this.occur = null;
    this.area = new XFAObjectArray();
    this.contentArea = new XFAObjectArray();
    this.draw = new XFAObjectArray();
    this.exclGroup = new XFAObjectArray();
    this.field = new XFAObjectArray();
    this.subform = new XFAObjectArray();
  }
  [$isUsable]() {
    if (!this[$extra]) {
      this[$extra] = {
        numberOfUse: 0,
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      return true;
    }
    return (
      !this.occur ||
      this.occur.max === -1 ||
      this[$extra].numberOfUse < this.occur.max
    );
  }
  [$cleanPage]() {