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 (!properties.cssFontInfo) {
      
      const newMapping = adjustMapping(
        charCodeToGlyphId,
        hasGlyph,
        glyphZeroId
      );
      this.toFontChar = newMapping.toFontChar;
      tables.cmap = {
        tag: "cmap",
        data: createCmapTable(newMapping.charCodeToGlyphId, numGlyphsOut),
      };
      if (!tables["OS/2"] || !validateOS2Table(tables["OS/2"], font)) {
        tables["OS/2"] = {
          tag: "OS/2",
          data: createOS2Table(
            properties,
            newMapping.charCodeToGlyphId,
            metricsOverride
          ),
        };
      }
    }
    if (!isTrueType) {
      try {
        
        cffFile = new Stream(tables["CFF "].data);
        const parser = new CFFParser(
          cffFile,