Attach (recommended) or Link to PDF file here:

Configuration:
- Web browser and its version: Chrome 63.0.3239.132 
- Operating system and its version: Windows 10
- PDF.js version: using your official demo project
- Is a browser extension: No

Steps to reproduce the problem:
1.  Just load attached pdf
2.

What is the expected behavior? (add screenshot)
[E-WG18_105147.pdf](https://github.com/mozilla/pdf.js/files/1634833/E-WG18_105147.pdf)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/29802177/34986271-3ca71a5c-fab7-11e7-95e8-1739dda3cd04.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

}
    width = width || this.defaultWidth;
    return shadow(this, "spaceWidth", width);
  }
  /**
   * @private
   */
  _charToGlyph(charcode, isSpace = false) {
    let fontCharCode, width, operatorListId;
    let widthCode = charcode;
    if (this.cMap && this.cMap.contains(charcode)) {
      widthCode = this.cMap.lookup(charcode);
    }
    width = this.widths[widthCode];
    width = isNum(width) ? width : this.defaultWidth;
    const vmetric = this.vmetrics && this.vmetrics[widthCode];
    let unicode = this.toUnicode.get(charcode) || charcode;
    if (typeof unicode === "number") {
      unicode = String.fromCharCode(unicode);
    }
    let isInFont = this.toFontChar[charcode] !== undefined;
    
    
    fontCharCode = this.toFontChar[charcode] || charcode;
    if (this.missingFile) {
      const glyphName =
        this.differences[charcode] || this.defaultEncoding[charcode];
      if (
        (glyphName === ".notdef" || glyphName === "") &&
        this.type === "Type1"