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 (numOfMetrics > numGlyphs) {
        info(
          `The numOfMetrics (${numOfMetrics}) should not be ` +
            `greater than the numGlyphs (${numGlyphs}).`
        );
        
        numOfMetrics = numGlyphs;
        header.data[34] = (numOfMetrics & 0xff00) >> 8;
        header.data[35] = numOfMetrics & 0x00ff;
      }
      const numOfSidebearings = numGlyphs - numOfMetrics;
      const numMissing =
        numOfSidebearings - ((metrics.length - numOfMetrics * 4) >> 1);
      if (numMissing > 0) {
        
        
        
        const entries = new Uint8Array(metrics.length + numMissing * 2);
        entries.set(metrics.data);
        if (dupFirstEntry) {
          
          entries[metrics.length] = metrics.data[2];
          entries[metrics.length + 1] = metrics.data[3];
        }
        metrics.data = entries;
      }
    }
    function sanitizeGlyph(