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):

baseFontCharCode,
            accentFontCharCode,
            accentOffset,
          };
        }
      }
      properties.seacMap = seacMap;
    }
    const unitsPerEm = 1 / (properties.fontMatrix || FONT_IDENTITY_MATRIX)[0];
    const builder = new OpenTypeFileBuilder("\x4F\x54\x54\x4F");
    
    builder.addTable("CFF ", font.data);
    
    builder.addTable("OS/2", createOS2Table(properties, newCharCodeToGlyphId));
    
    builder.addTable("cmap", createCmapTable(newCharCodeToGlyphId, numGlyphs));
    
    builder.addTable(
      "head",
      "\x00\x01\x00\x00" + 
        "\x00\x00\x10\x00" + 
        "\x00\x00\x00\x00" + 
        "\x5F\x0F\x3C\xF5" + 
        "\x00\x00" + 
        safeString16(unitsPerEm) + 
        "\x00\x00\x00\x00\x9e\x0b\x7e\x27" + 
        "\x00\x00\x00\x00\x9e\x0b\x7e\x27" + 
        "\x00\x00" + 
        safeString16(properties.descent) + 
        "\x0F\xFF" +