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 locaEntries = [];
      
      for (i = 0, j = 0; i < numGlyphs + 1; i++, j += itemSize) {
        let offset = itemDecode(locaData, j);
        if (offset > oldGlyfDataLength) {
          offset = oldGlyfDataLength;
        }
        locaEntries.push({
          index: i,
          offset,
          endOffset: 0,
        });
      }
      locaEntries.sort((a, b) => {
        return a.offset - b.offset;
      });
      
      
      
      for (i = 0; i < numGlyphs; i++) {
        locaEntries[i].endOffset = locaEntries[i + 1].offset;
      }
      
      locaEntries.sort((a, b) => {
        return a.index - b.index;
      });
      const missingGlyphs = Object.create(null);
      let writeOffset = 0;
      itemEncode(locaData, 0, writeOffset);
      for (i = 0, j = itemSize; i < numGlyphs; i++, j += itemSize) {