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 

return Object.values(this._glyphCache);
  }
  /**
   * Encode a js string using font encoding.
   * The resulting array contains an encoded string at even positions
   * (can be empty) and a non-encoded one at odd positions.
   * @param {String} a js string.
   * @returns {Array<String>} an array of encoded strings or non-encoded ones.
   */
  encodeString(str) {
    const buffers = [];
    const currentBuf = [];
    
    
    
    
    const hasCurrentBufErrors = () => buffers.length % 2 === 1;
    const getCharCode =
      this.toUnicode instanceof IdentityToUnicodeMap
        ? unicode => this.toUnicode.charCodeOf(unicode)
        : unicode => this.toUnicode.charCodeOf(String.fromCodePoint(unicode));
    for (let i = 0, ii = str.length; i < ii; i++) {
      const unicode = str.codePointAt(i);
      if (unicode > 0xd7ff && (unicode < 0xe000 || unicode > 0xfffd)) {