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):

"hmtx",
      (function fontFieldsHmtx() {
        const charstrings = font.charstrings;
        const cffWidths = font.cff ? font.cff.widths : null;
        let hmtx = "\x00\x00\x00\x00"; 
        for (let i = 1, ii = numGlyphs; i < ii; i++) {
          let width = 0;
          if (charstrings) {
            const charstring = charstrings[i - 1];
            width = "width" in charstring ? charstring.width : 0;
          } else if (cffWidths) {
            width = Math.ceil(cffWidths[i] || 0);
          }
          hmtx += string16(width) + string16(0);
        }
        return hmtx;
      })()
    );
    
    builder.addTable(
      "maxp",
      "\x00\x00\x50\x00" + string16(numGlyphs) 
    ); 
    
    builder.addTable("name", createNameTable(fontName));
    
    builder.addTable("post", createPostTable(properties));
    return builder.toArray();
  }
  get spaceWidth() {