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)


this.handler = new XFAObjectArray();
    this.hyphenation = new XFAObjectArray();
    this.image = new XFAObjectArray();
    this.imageEdit = new XFAObjectArray();
    this.integer = new XFAObjectArray();
    this.issuers = new XFAObjectArray();
    this.items = new XFAObjectArray();
    this.keep = new XFAObjectArray();
    this.keyUsage = new XFAObjectArray();
    this.line = new XFAObjectArray();
    this.linear = new XFAObjectArray();
    this.lockDocument = new XFAObjectArray();
    this.manifest = new XFAObjectArray();
    this.margin = new XFAObjectArray();
    this.mdp = new XFAObjectArray();
    this.medium = new XFAObjectArray();
    this.message = new XFAObjectArray();
    this.numericEdit = new XFAObjectArray();
    this.occur = new XFAObjectArray();
    this.oid = new XFAObjectArray();
    this.oids = new XFAObjectArray();
    this.overflow = new XFAObjectArray();
    this.pageArea = new XFAObjectArray();
    this.pageSet = new XFAObjectArray();
    this.para = new XFAObjectArray();
    this.passwordEdit = new XFAObjectArray();
    this.pattern = new XFAObjectArray();
    this.picture = new XFAObjectArray();
    this.radial = new XFAObjectArray();
    this.reason = new XFAObjectArray();