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 tag = file.getString(4);
      const checksum = file.getInt32() >>> 0;
      const offset = file.getInt32() >>> 0;
      const length = file.getInt32() >>> 0;
      
      const previousPosition = file.pos;
      file.pos = file.start ? file.start : 0;
      file.skip(offset);
      const data = file.getBytes(length);
      file.pos = previousPosition;
      if (tag === "head") {
        
        data[8] = data[9] = data[10] = data[11] = 0;
        data[17] |= 0x20; 
      }
      return {
        tag,
        checksum,
        length,
        offset,
        data,
      };
    }
    function readOpenTypeHeader(ttf) {