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):

if (!properties.cssFontInfo) {
      
      const newMapping = adjustMapping(
        charCodeToGlyphId,
        hasGlyph,
        glyphZeroId
      );
      this.toFontChar = newMapping.toFontChar;
      tables.cmap = {
        tag: "cmap",
        data: createCmapTable(newMapping.charCodeToGlyphId, numGlyphsOut),
      };
      if (!tables["OS/2"] || !validateOS2Table(tables["OS/2"], font)) {
        tables["OS/2"] = {
          tag: "OS/2",
          data: createOS2Table(
            properties,
            newMapping.charCodeToGlyphId,
            metricsOverride
          ),
        };
      }
    }
    if (!isTrueType) {
      try {
        
        cffFile = new Stream(tables["CFF "].data);
        const parser = new CFFParser(
          cffFile,