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 metricsOverride = {
      unitsPerEm: int16(tables.head.data[18], tables.head.data[19]),
      yMax: int16(tables.head.data[42], tables.head.data[43]),
      yMin: signedInt16(tables.head.data[38], tables.head.data[39]),
      ascent: signedInt16(tables.hhea.data[4], tables.hhea.data[5]),
      descent: signedInt16(tables.hhea.data[6], tables.hhea.data[7]),
      lineGap: signedInt16(tables.hhea.data[8], tables.hhea.data[9]),
    };
    
    this.ascent = metricsOverride.ascent / metricsOverride.unitsPerEm;
    this.descent = metricsOverride.descent / metricsOverride.unitsPerEm;
    this.lineGap = metricsOverride.lineGap / metricsOverride.unitsPerEm;
    if (this.cssFontInfo && this.cssFontInfo.lineHeight) {
      this.lineHeight = this.cssFontInfo.metrics.lineHeight;
      this.lineGap = this.cssFontInfo.metrics.lineGap;
    } else {
      this.lineHeight = this.ascent - this.descent + this.lineGap;
    }
    
    if (tables.post) {
      readPostScriptTable(tables.post, properties, numGlyphs);
    }
    
    tables.post = {
      tag: "post",
      data: createPostTable(properties),
    };
    const charCodeToGlyphId = [];
    
    function hasGlyph(glyphId) {