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 

"hmtx",
      (function fontFieldsHmtx() {
        const charstrings = font.charstrings;
        const cffWidths = font.cff ? font.cff.widths : null;
        let hmtx = "\x00\x00\x00\x00"; 
        for (let i = 1, ii = numGlyphs; i < ii; i++) {
          let width = 0;
          if (charstrings) {
            const charstring = charstrings[i - 1];
            width = "width" in charstring ? charstring.width : 0;
          } else if (cffWidths) {
            width = Math.ceil(cffWidths[i] || 0);
          }
          hmtx += string16(width) + string16(0);
        }
        return hmtx;
      })()
    );
    
    builder.addTable(
      "maxp",
      "\x00\x00\x50\x00" + string16(numGlyphs) 
    ); 
    
    builder.addTable("name", createNameTable(fontName));
    
    builder.addTable("post", createPostTable(properties));
    return builder.toArray();
  }
  get spaceWidth() {