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)


"font",
      "dimensions",
      "position",
      "rotate",
      "anchorType",
      "presence",
      "margin",
      "hAlign"
    );
    setMinMaxDimensions(this, style);
    const classNames = ["xfaField"];
    
    if (this.font) {
      classNames.push("xfaFont");
    }
    if (isPrintOnly(this)) {
      classNames.push("xfaPrintOnly");
    }
    const attributes = {
      style,
      id: this[$uid],
      class: classNames,
    };
    setAccess(this, classNames);
    if (this.name) {
      attributes.xfaName = this.name;
    }
    const children = [];
    const html = {
      name: "div",