Attach (recommended) or Link to PDF file here:
http://education.ohio.gov/getattachment/Topics/Special-Education/Preschool-Special-Education/ETR-Preschool-Planning-Form.pdf.aspx

- Web browser and its version: Firefox 89.0.1
- Operating system and its version: Windows 10 10.0.19043.1052
- PDF.js version: commit 5d251a3a3e7bfaa8fbfa07f0b7f9901eb3f999d9
- Is a browser extension: No

Steps to reproduce the problem:
1. Enable XFA support
2. Open form

What is the expected behavior? (add screenshot)
Shapes stay inside table cells
![image](https://user-images.githubusercontent.com/7104454/122572782-1252a580-d01c-11eb-9d0f-5fed46d6f2fe.png)

What went wrong? (add screenshot)
Shapes fall outside cells (among other issues)
![image](https://user-images.githubusercontent.com/7104454/122572885-2d251a00-d01c-11eb-8863-fa3b9969f0ea.png)

const parent = this[$getParent]();
    if (parent instanceof Field) {
      if (parent.ui && parent.ui.imageEdit) {
        if (!this.image) {
          this.image = new Image({});
        }
        this.image[$content] = value[$content];
        return;
      }
    }
    const valueName = value[$nodeName];
    if (this[valueName] !== null) {
      this[valueName][$content] = value[$content];
      return;
    }
    
    for (const name of Object.getOwnPropertyNames(this)) {
      const obj = this[name];
      if (obj instanceof XFAObject) {
        this[name] = null;
        this[$removeChild](obj);
      }
    }
    this[value[$nodeName]] = value;
    this[$appendChild](value);
  }
  [$text]() {