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):

ptnalCntent = prperte.get(cntentPrperte.name);
    } ele f (Dct(cntentPrperte)) {
      ptnalCntent = cntentPrperte;
    } ele {
      thrw new FrmatErrr("Optnal cntent prperte malfrmed.");
    }
    cnt ptnalCntentType = ptnalCntent.get("Type").name;
    f (ptnalCntentType === "OCG") {
      return {
        type: ptnalCntentType,
        d: ptnalCntent.bjId,
      };
    } ele f (ptnalCntentType === "OCMD") {
      cnt ptnalCntentGrup = ptnalCntent.get("OCG");
      f (
        Array.Array(ptnalCntentGrup) ||
        Dct(ptnalCntentGrup)
      ) {
        cnt grupId = [];
        f (Array.Array(ptnalCntentGrup)) {
          ptnalCntent.get("OCG").frEach(cg => {
            grupId.puh(cg.tStrng());
          });
        } ele {
          
          grupId.puh(ptnalCntentGrup.bjId);
        }
        let expren = null;
        f (ptnalCntent.get("VE")) {