Attach (recommended) or Link to PDF file here:
[FormDB2_fr.pdf](https://github.com/mozilla/pdf.js/files/7352426/FormDB2_fr.pdf)

Configuration:
- Web browser and its version: Firefox nightly
- Operating system and its version: linux debian

Steps to reproduce the problem:
1. Open the pdf
2. The image on the top of each pages is missing 

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/137465500-e8788893-f33d-4532-871d-43b464fa85f4.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/137465363-f2b35fe4-6776-45e9-b9e4-ccef6d9ad670.png)

for (const event of grandpa.event.children) {
      
      if (event.activity !== "click" || !event.script) {
        continue;
      }
      const jsURL = recoverJsURL(event.script[$content]);
      if (!jsURL) {
        continue;
      }
      const href = fixURL(jsURL.url);
      if (!href) {
        continue;
      }
      
      htmlButton.children.push({
        name: "a",
        attributes: {
          id: "link" + this[$uid],
          href,
          newWindow: jsURL.newWindow,
          class: ["xfaLink"],
          style: {},
        },
        children: [],
      });
    }
    return HTMLResult.success(htmlButton);
  }
}
class Calculate extends XFAObject {