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 namesRecordCount = strings.length * platforms.length;
  let nameTable =
    "\x00\x00" + 
    string16(namesRecordCount) + 
    string16(namesRecordCount * 12 + 6); 
  
  let strOffset = 0;
  for (i = 0, ii = platforms.length; i < ii; i++) {
    const strs = names[i];
    for (j = 0, jj = strs.length; j < jj; j++) {
      str = strs[j];
      const nameRecord =
        platforms[i] + 
        encodings[i] + 
        languages[i] + 
        string16(j) + 
        string16(str.length) +
        string16(strOffset);
      nameTable += nameRecord;
      strOffset += str.length;
    }
  }
  nameTable += strings.join("") + stringsUnicode.join("");
  return nameTable;
}
/**
 * 'Font' is the class the outside world should use, it encapsulate all the font
 * decoding logics whatever type it is (assuming the font type is supported).
 */
class Font {