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):

} else {
            for (j = 0; j < n; j++) {
              stack.push(data[i++]);
            }
          }
        } else if ((op & 0xf8) === 0xb8) {
          
          n = op - 0xb8 + 1;
          if (inFDEF || inELSE) {
            i += n * 2;
          } else {
            for (j = 0; j < n; j++) {
              b = data[i++];
              stack.push((b << 8) | data[i++]);
            }
          }
        } else if (op === 0x2b && !tooComplexToFollowFunctions) {
          
          if (!inFDEF && !inELSE) {
            
            funcId = stack[stack.length - 1];
            if (isNaN(funcId)) {
              info("TT: CALL empty stack (or invalid entry).");
            } else {
              ttContext.functionsUsed[funcId] = true;
              if (funcId in ttContext.functionsStackDeltas) {
                const newStackLength =
                  stack.length + ttContext.functionsStackDeltas[funcId];
                if (newStackLength < 0) {
                  warn("TT: CALL invalid functions stack delta.");