Attach (recommended) or Link to PDF file here:
[test.pdf](https://github.com/mozilla/pdf.js/files/6715502/test.pdf)

Configuration:
- Web browser and its version: Google Chrome Version 91.0.4472.114 
- Operating system and its version: Windows 10 Enterprise
- PDF.js version: 
- Is a browser extension: yes

Steps to reproduce the problem:
1. download file
2. open file



What is the expected behavior? (add screenshot)
show symbol
![image](https://user-images.githubusercontent.com/50500976/123409847-55ca8800-d5b7-11eb-9e5b-c7f3b33c00e1.png)

What went wrong? (add screenshot)
Does not show symbol
![image](https://user-images.githubusercontent.com/50500976/123409707-274cad00-d5b7-11eb-9a64-b11dcf3cdc3f.png)
Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension): Latest Version Chrome extension

glyphId,
          });
        }
      } else {
        warn("cmap table has unsupported format: " + format);
        return {
          platformId: -1,
          encodingId: -1,
          mappings: [],
          hasShortCmap: false,
        };
      }
      
      mappings.sort(function (a, b) {
        return a.charCode - b.charCode;
      });
      for (let i = 1; i < mappings.length; i++) {
        if (mappings[i - 1].charCode === mappings[i].charCode) {
          mappings.splice(i, 1);
          i--;
        }
      }
      return {
        platformId: potentialTable.platformId,
        encodingId: potentialTable.encodingId,
        mappings,
        hasShortCmap,
      };
    }
    function sanitizeMetrics(file, header, metrics, numGlyphs, dupFirstEntry) {