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):

mappings: [],
          hasShortCmap: false,
        };
      }
      let segment;
      let start = (file.start ? file.start : 0) + cmap.offset;
      file.pos = start;
      file.skip(2); 
      const numTables = file.getUint16();
      let potentialTable;
      let canBreak = false;
      
      
      
      
      
      
      for (let i = 0; i < numTables; i++) {
        const platformId = file.getUint16();
        const encodingId = file.getUint16();
        const offset = file.getInt32() >>> 0;
        let useTable = false;
        
        
        if (
          potentialTable &&
          potentialTable.platformId === platformId &&
          potentialTable.encodingId === encodingId
        ) {
          continue;