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):

j = 10,
        flagsCount = 0;
      for (i = 0; i < contoursCount; i++) {
        const endPoint = (glyf[j] << 8) | glyf[j + 1];
        flagsCount = endPoint + 1;
        j += 2;
      }
      
      const instructionsStart = j;
      const instructionsLength = (glyf[j] << 8) | glyf[j + 1];
      glyphProfile.sizeOfInstructions = instructionsLength;
      j += 2 + instructionsLength;
      const instructionsEnd = j;
      
      let coordinatesLength = 0;
      for (i = 0; i < flagsCount; i++) {
        const flag = glyf[j++];
        if (flag & 0xc0) {
          
          glyf[j - 1] = flag & 0x3f;
        }
        let xLength = 2;
        if (flag & 2) {
          xLength = 1;
        } else if (flag & 16) {
          xLength = 0;
        }
        let yLength = 2;
        if (flag & 4) {
          yLength = 1;