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):

let glyphsIds = "";
  let bias = 0;
  let range, start, end, codes;
  for (i = 0, ii = bmpLength; i < ii; i++) {
    range = ranges[i];
    start = range[0];
    end = range[1];
    startCount += string16(start);
    endCount += string16(end);
    codes = range[2];
    let contiguous = true;
    for (j = 1, jj = codes.length; j < jj; ++j) {
      if (codes[j] !== codes[j - 1] + 1) {
        contiguous = false;
        break;
      }
    }
    if (!contiguous) {
      const offset = (segCount - i) * 2 + bias * 2;
      bias += end - start + 1;
      idDeltas += string16(0);
      idRangeOffsets += string16(offset);
      for (j = 0, jj = codes.length; j < jj; ++j) {
        glyphsIds += string16(codes[j]);
      }
    } else {
      const startCode = codes[0];
      idDeltas += string16((startCode - start) & 0xffff);
      idRangeOffsets += string16(0);
    }