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):

functn (cmap) {
          f (cmap ntancef IdenttyCMap) {
            return new IdenttyTUncdeMap(0, 0xffff);
          }
          var map = new Array(cmap.length);
           Cnvert UTF-16BE
           NOTE: cmap can be a pare array,  ue frEach ntead f
           `fr(;;)` t terate ver all key.
          cmap.frEach(functn (charCde, tken) {
            var tr = [];
            fr (var k = 0; k < tken.length; k = 2) {
              var w1 = (tken.charCdeAt(k) << 8) | tken.charCdeAt(k  1);
              f ((w1 & 0xf800) !== 0xd800) {
                 w1 < 0xD800 |
                tr.puh(w1);
                cntnue;
              }
              k = 2;
              var w2 = (tken.charCdeAt(k) << 8) | tken.charCdeAt(k  1);
              tr.puh(((w1 & 0x3ff) << 10)  (w2 & 0x3ff)  0x10000);
            }
            map[charCde] = Strng.frmCdePnt.apply(Strng, tr);
          });
          return new TUncdeMap(map);
        },
        rean => {
          f (rean ntancef AbrtExceptn) {
            return null;
          }
          f (th.ptn.gnreErrr) {