Attach (recommended) or Link to PDF file here:
https://www.canada.ca/content/dam/ircc/migration/ircc/english/pdf/kits/forms/eimm5669e.pdf
[eimm5669e.pdf](https://github.com/mozilla/pdf.js/files/7225677/eimm5669e.2.pdf)

Configuration:
- Web browser and its version: Firefox nightly
- Operating system and its version: Linux Debian

Steps to reproduce the problem:
1. Look at the bottom of page 2

this.pageSet = null;
    this.para = null;
    this.traversal = null;
    this.validate = null;
    this.variables = null;
    this.area = new XFAObjectArray();
    this.breakAfter = new XFAObjectArray();
    this.breakBefore = new XFAObjectArray();
    this.connect = new XFAObjectArray();
    this.draw = new XFAObjectArray();
    this.event = new XFAObjectArray();
    this.exObject = new XFAObjectArray();
    this.exclGroup = new XFAObjectArray();
    this.field = new XFAObjectArray();
    this.proto = new XFAObjectArray();
    this.setProperty = new XFAObjectArray();
    this.subform = new XFAObjectArray();
    this.subformSet = new XFAObjectArray();
  }
  [$getSubformParent]() {
    const parent = this[$getParent]();
    if (parent instanceof SubformSet) {
      return parent[$getSubformParent]();
    }
    return parent;
  }
  [$isBindable]() {
    return true;
  }
  [$isThereMoreWidth]() {