Attach (recommended) or Link to PDF file here:
[双引号不正常.pdf](https://github.com/mozilla/pdf.js/files/3533108/default.pdf)


Configuration:
- Web browser and its version:  IE11 , chrome 
- Operating system and its version:  win7
- PDF.js version:  master
- Is a browser extension: nothing 
teps to reproduce the problem:
1. viewer.html web  online preview


What is the expected behavior? (add screenshot)
Displayed in normal characters.

What went wrong? (add screenshot)
![20190823143813](https://user-images.githubusercontent.com/6269307/63571860-062e6600-c5b4-11e9-9fff-75d65cf6bade.png)

Not only the two characters I took screenshots, but also a lot of garbled Chinese punctuation. For example, the Chinese 《》 symbol. But these garbled characters only appear in some specific very old pdf files.

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):nothing 

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,