Attach (recommended) or Link to PDF file here:
[chinese.pdf](https://github.com/mozilla/pdf.js/files/6404389/download.1.pdf)

Configuration:
- Web browser and its version:90.0.4430.93
- Operating system and its version: mac 10.15.5
- PDF.js version: 2.9.146
- Is a browser extension:no

Steps to reproduce the problem:
1. The Chinese in the attachment cannot be rendered

Brower ✅
![image](https://user-images.githubusercontent.com/13477114/116678074-81782a00-a9db-11eb-8719-74f48fcebc2b.png)

PDF.js ❌ [https://mozilla.github.io/pdf.js/web/viewer.html](https://mozilla.github.io/pdf.js/web/viewer.html)
![image](https://user-images.githubusercontent.com/13477114/116678212-a371ac80-a9db-11eb-847f-dd1ad7752c13.png)


What is the expected behavior? (add screenshot)
**The Chinese character can be rendered**
What went wrong? (add screenshot)
**All of the Chinese character cannot be rendered**
Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

correctlySorted = false;
            }
          }
          if (correctlySorted) {
            canBreak = true;
          }
        }
        if (useTable) {
          potentialTable = {
            platformId,
            encodingId,
            offset,
          };
        }
        if (canBreak) {
          break;
        }
      }
      if (potentialTable) {
        file.pos = start + potentialTable.offset;
      }
      if (!potentialTable || file.peekByte() === -1) {
        warn("Could not find a preferred cmap table.");
        return {
          platformId: -1,
          encodingId: -1,
          mappings: [],
          hasShortCmap: false,
        };
      }