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):

++ifLevel;
        } else if (op === 0x1b) {
          
          inELSE = ifLevel;
        } else if (op === 0x59) {
          
          if (inELSE === ifLevel) {
            inELSE = 0;
          }
          --ifLevel;
        } else if (op === 0x1c) {
          
          if (!inFDEF && !inELSE) {
            const offset = stack[stack.length - 1];
            
            if (offset > 0) {
              i += offset - 1;
            }
          }
        }
        
        if (!inFDEF && !inELSE) {
          let stackDelta = 0;
          if (op <= 0x8e) {
            stackDelta = TTOpsStackDeltas[op];
          } else if (op >= 0xc0 && op <= 0xdf) {
            stackDelta = -1;
          } else if (op >= 0xe0) {
            stackDelta = -2;
          }