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 

let glyphsIds = "";
  let bias = 0;
  let range, start, end, codes;
  for (i = 0, ii = bmpLength; i < ii; i++) {
    range = ranges[i];
    start = range[0];
    end = range[1];
    startCount += string16(start);
    endCount += string16(end);
    codes = range[2];
    let contiguous = true;
    for (j = 1, jj = codes.length; j < jj; ++j) {
      if (codes[j] !== codes[j - 1] + 1) {
        contiguous = false;
        break;
      }
    }
    if (!contiguous) {
      const offset = (segCount - i) * 2 + bias * 2;
      bias += end - start + 1;
      idDeltas += string16(0);
      idRangeOffsets += string16(offset);
      for (j = 0, jj = codes.length; j < jj; ++j) {
        glyphsIds += string16(codes[j]);
      }
    } else {
      const startCode = codes[0];
      idDeltas += string16((startCode - start) & 0xffff);
      idRangeOffsets += string16(0);
    }