Attach (recommended) or Link to PDF file here:
[test.pdf](https://github.com/mozilla/pdf.js/files/6270827/test.pdf)
Configuration:
- Web browser and its version:chrome 89
- Operating system and its version:win10
- PDF.js version: 2.4/2.7/2.8 no working
- Is a browser extension: no 

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/18545199/113852392-1ae26080-97cf-11eb-9dc9-0cecf52d267b.png)

What went wrong? (add screenshot)
![1617791294(1)](https://user-images.githubusercontent.com/18545199/113852355-10c06200-97cf-11eb-8672-598750f1093a.jpg)


console this log : **FormatError: TrueType Collection does not contain "DCWGQU+CambriaMath" font** 

any solution?thanks
var fontCharCode, width, operatorListId;
      var widthCode = charcode;
      if (this.cMap && this.cMap.contains(charcode)) {
        widthCode = this.cMap.lookup(charcode);
      }
      width = this.widths[widthCode];
      width = isNum(width) ? width : this.defaultWidth;
      var vmetric = this.vmetrics && this.vmetrics[widthCode];
      let unicode =
        this.toUnicode.get(charcode) ||
        this.fallbackToUnicode.get(charcode) ||
        charcode;
      if (typeof unicode === "number") {
        unicode = String.fromCharCode(unicode);
      }
      var isInFont = charcode in this.toFontChar;
      
      
      fontCharCode = this.toFontChar[charcode] || charcode;
      if (this.missingFile) {
        const glyphName =
          this.differences[charcode] || this.defaultEncoding[charcode];
        if (
          (glyphName === ".notdef" || glyphName === "") &&
          this.type === "Type1"
        ) {
          
          
          fontCharCode = 0x20;
        }