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)


const parent = this[$getParent]();
    const style = Object.create(null);
    let propName = "color";
    if (parent instanceof Border) {
      propName = "background";
    }
    if (parent instanceof Rectangle || parent instanceof Arc) {
      propName = "fill";
      style.fill = "transparent";
    }
    for (const name of Object.getOwnPropertyNames(this)) {
      if (name === "extras" || name === "color") {
        continue;
      }
      const obj = this[name];
      if (!(obj instanceof XFAObject)) {
        continue;
      }
      style[propName] = obj[$toStyle](this.color);
      return style;
    }
    if (this.color) {
      style[propName] = this.color[$toStyle]();
    }
    return style;
  }
}
class Filter extends XFAObject {