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):

const GlyphMapForStandardFonts = getGlyphMapForStandardFonts();
          for (const charCode in GlyphMapForStandardFonts) {
            map[+charCode] = GlyphMapForStandardFonts[charCode];
          }
        }
      }
      this.toFontChar = map;
    }
    amendFallbackToUnicode(properties);
    this.loadedName = fontName.split("-")[0];
    this.fontType = getFontType(type, subtype, properties.isStandardFont);
  }
  checkAndRepair(name, font, properties) {
    const VALID_TABLES = [
      "OS/2",
      "cmap",
      "head",
      "hhea",
      "hmtx",
      "maxp",
      "name",
      "post",
      "loca",
      "glyf",
      "fpgm",
      "prep",
      "cvt ",
      "CFF ",
    ];
    function readTables(file, numTables) {