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 

const unitsPerEm =
    override.unitsPerEm ||
    1 / (properties.fontMatrix || FONT_IDENTITY_MATRIX)[0];
  
  
  const scale = properties.ascentScaled
    ? 1.0
    : unitsPerEm / PDF_GLYPH_SPACE_UNITS;
  const typoAscent =
    override.ascent || Math.round(scale * (properties.ascent || bbox[3]));
  let typoDescent =
    override.descent || Math.round(scale * (properties.descent || bbox[1]));
  if (typoDescent > 0 && properties.descent > 0 && bbox[1] < 0) {
    typoDescent = -typoDescent; 
  }
  const winAscent = override.yMax || typoAscent;
  const winDescent = -override.yMin || -typoDescent;
  return (
    "\x00\x03" + 
    "\x02\x24" + 
    "\x01\xF4" + 
    "\x00\x05" + 
    "\x00\x00" + 
    "\x02\x8A" + 
    "\x02\xBB" + 
    "\x00\x00" + 
    "\x00\x8C" + 
    "\x02\x8A" + 
    "\x02\xBB" + 
    "\x00\x00" +