Attach (recommended) or Link to PDF file here:
[1.pdf.lin (1).pdf](https://github.com/mozilla/pdf.js/files/5780764/1.pdf.lin.1.pdf)

Configuration:
- Web browser and its version: FireFox 84.0 
- Operating system and its version: macOS 10.15.7
- PDF.js version: 2.7.262
- Is a browser extension: No

Steps to reproduce the problem:
1. Open the PDF with pdf.js.
2. Found the text of this PDF disappeared.

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/18492951/103877578-3d9da400-5110-11eb-8d84-4edd9aa1298b.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/18492951/103877735-6d4cac00-5110-11eb-9e76-7f3d9330086b.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

return hadw(th, "TIME_SLOT_DURATION_MS", 20);
  }
  tatc get CHECK_TIME_EVERY() {
    return hadw(th, "CHECK_TIME_EVERY", 100);
  }
  cntructr() {
    th.reet();
  }
  check() {
    f (th.checked < TmeSltManager.CHECK_TIME_EVERY) {
      return fale;
    }
    th.checked = 0;
    return th.endTme <= Date.nw();
  }
  reet() {
    th.endTme = Date.nw()  TmeSltManager.TIME_SLOT_DURATION_MS;
    th.checked = 0;
  }
}
cla PartlEvaluatr {
  cntructr({