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):

}
  if (trailingRangesCount > 0) {
    endCount += "\xFF\xFF";
    startCount += "\xFF\xFF";
    idDeltas += "\x00\x01";
    idRangeOffsets += "\x00\x00";
  }
  const format314 =
    "\x00\x00" + 
    string16(2 * segCount) +
    string16(searchParams.range) +
    string16(searchParams.entry) +
    string16(searchParams.rangeShift) +
    endCount +
    "\x00\x00" +
    startCount +
    idDeltas +
    idRangeOffsets +
    glyphsIds;
  let format31012 = "";
  let header31012 = "";
  if (numTables > 1) {
    cmap +=
      "\x00\x03" + 
      "\x00\x0A" + 
      string32(4 + numTables * 8 + 4 + format314.length); 
    format31012 = "";
    for (i = 0, ii = ranges.length; i < ii; i++) {
      range = ranges[i];
      start = range[0];