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
if (properties.hasIncludedToUnicodeMap) {
    return; 
  }
  if (properties.hasEncoding) {
    return; 
  }
  if (builtInEncoding === properties.defaultEncoding) {
    return; 
  }
  if (properties.toUnicode instanceof IdentityToUnicodeMap) {
    return;
  }
  var toUnicode = [],
    glyphsUnicodeMap = getGlyphsUnicode();
  for (var charCode in builtInEncoding) {
    var glyphName = builtInEncoding[charCode];
    var unicode = getUnicodeForGlyph(glyphName, glyphsUnicodeMap);
    if (unicode !== -1) {
      toUnicode[charCode] = String.fromCharCode(unicode);
    }
  }
  properties.toUnicode.amend(toUnicode);
}
function getFontType(type, subtype) {