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):

) {
        
        
        fontCharCode = 0x20;
      }
      fontCharCode = mapSpecialUnicodeValues(fontCharCode);
    }
    if (this.isType3Font) {
      
      operatorListId = fontCharCode;
    }
    let accent = null;
    if (this.seacMap && this.seacMap[charcode]) {
      isInFont = true;
      const seac = this.seacMap[charcode];
      fontCharCode = seac.baseFontCharCode;
      accent = {
        fontChar: String.fromCodePoint(seac.accentFontCharCode),
        offset: seac.accentOffset,
      };
    }
    let fontChar = "";
    if (typeof fontCharCode === "number") {
      if (fontCharCode <= 0x10ffff) {
        fontChar = String.fromCodePoint(fontCharCode);
      } else {
        warn(`charToGlyph - invalid fontCharCode: ${fontCharCode}`);
      }
    }
    let glyph = this._glyphCache[charcode];