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)


constructor(attributes) {
    super(TEMPLATE_NS_ID, "color",  true);
    this.cSpace = getStringOption(attributes.cSpace, ["SRGB"]);
    this.id = attributes.id || "";
    this.use = attributes.use || "";
    this.usehref = attributes.usehref || "";
    this.value = attributes.value ? getColor(attributes.value) : "";
    this.extras = null;
  }
  [$hasSettableValue]() {
    return false;
  }
  [$toStyle]() {
    return this.value
      ? Util.makeHexColor(this.value.r, this.value.g, this.value.b)
      : null;
  }
}
class Comb extends XFAObject {