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 

this.capHeight = properties.capHeight / PDF_GLYPH_SPACE_UNITS;
    this.ascent = properties.ascent / PDF_GLYPH_SPACE_UNITS;
    this.descent = properties.descent / PDF_GLYPH_SPACE_UNITS;
    this.lineHeight = this.ascent - this.descent;
    this.fontMatrix = properties.fontMatrix;
    this.bbox = properties.bbox;
    this.defaultEncoding = properties.defaultEncoding;
    this.toUnicode = properties.toUnicode;
    this.toFontChar = [];
    if (properties.type === "Type3") {
      for (let charCode = 0; charCode < 256; charCode++) {
        this.toFontChar[charCode] =
          this.differences[charCode] || properties.defaultEncoding[charCode];
      }
      this.fontType = FontType.TYPE3;
      return;
    }
    this.cidEncoding = properties.cidEncoding;
    this.vertical = !!properties.vertical;
    if (this.vertical) {
      this.vmetrics = properties.vmetrics;
      this.defaultVMetrics = properties.defaultVMetrics;
    }
    if (!file || file.isEmpty) {
      if (file) {
        
        
        warn('Font file is empty in "' + name + '" (' + this.loadedName + ")");
      }
      this.fallbackToSystemFont(properties);