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 

++ifLevel;
        } else if (op === 0x1b) {
          
          inELSE = ifLevel;
        } else if (op === 0x59) {
          
          if (inELSE === ifLevel) {
            inELSE = 0;
          }
          --ifLevel;
        } else if (op === 0x1c) {
          
          if (!inFDEF && !inELSE) {
            const offset = stack[stack.length - 1];
            
            if (offset > 0) {
              i += offset - 1;
            }
          }
        }
        
        if (!inFDEF && !inELSE) {
          let stackDelta = 0;
          if (op <= 0x8e) {
            stackDelta = TTOpsStackDeltas[op];
          } else if (op >= 0xc0 && op <= 0xdf) {
            stackDelta = -1;
          } else if (op >= 0xe0) {
            stackDelta = -2;
          }