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)


if (this.href || !this[$content]) {
      
      
      
      
      return HTMLResult.EMPTY;
    }
    
    if (this.transferEncoding === "base64") {
      const buffer = stringToBytes(atob(this[$content]));
      const blob = new Blob([buffer], { type: this.contentType });
      return HTMLResult.success({
        name: "img",
        attributes: {
          class: ["xfaImage"],
          style: {},
          src: URL.createObjectURL(blob),
        },
      });
    }
    return HTMLResult.EMPTY;
  }
}
class ImageEdit extends XFAObject {