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 

j = 10,
        flagsCount = 0;
      for (i = 0; i < contoursCount; i++) {
        const endPoint = (glyf[j] << 8) | glyf[j + 1];
        flagsCount = endPoint + 1;
        j += 2;
      }
      
      const instructionsStart = j;
      const instructionsLength = (glyf[j] << 8) | glyf[j + 1];
      glyphProfile.sizeOfInstructions = instructionsLength;
      j += 2 + instructionsLength;
      const instructionsEnd = j;
      
      let coordinatesLength = 0;
      for (i = 0; i < flagsCount; i++) {
        const flag = glyf[j++];
        if (flag & 0xc0) {
          
          glyf[j - 1] = flag & 0x3f;
        }
        let xLength = 2;
        if (flag & 2) {
          xLength = 1;
        } else if (flag & 16) {
          xLength = 0;
        }
        let yLength = 2;
        if (flag & 4) {
          yLength = 1;