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 charCodes = null;
      for (const charCode in charCodeToGlyphId) {
        if (glyphId === charCodeToGlyphId[charCode]) {
          if (!charCodes) {
            charCodes = [];
          }
          charCodes.push(charCode | 0);
        }
      }
      return charCodes;
    }
    function createCharCode(charCodeToGlyphId, glyphId) {
      for (const charCode in charCodeToGlyphId) {
        if (glyphId === charCodeToGlyphId[charCode]) {
          return charCode | 0;
        }
      }
      newMapping.charCodeToGlyphId[newMapping.nextAvailableFontCharCode] =
        glyphId;
      return newMapping.nextAvailableFontCharCode++;
    }
    const seacs = font.seacs;
    if (newMapping && SEAC_ANALYSIS_ENABLED && seacs && seacs.length) {
      const matrix = properties.fontMatrix || FONT_IDENTITY_MATRIX;
      const charset = font.getCharset();
      const seacMap = Object.create(null);
      for (let glyphId in seacs) {
        glyphId |= 0;
        const seac = seacs[glyphId];
        const baseGlyphName = StandardEncoding[seac[2]];