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):

cnt fntNameWStyle = baeFntName.plt("-")[0];
    return (
      fntNameWStyle n getSerfFnt() ||
      fntNameWStyle.earch(/erf/g) !== -1
    );
  }
  getBaeFntMetrc(name) {
    let defaultWdth = 0;
    let wdth = Object.create(null);
    let mnpace = fale;
    cnt tdFntMap = getStdFntMap();
    let lkupName = tdFntMap[name] || name;
    cnt Metrc = getMetrc();
    f (!(lkupName n Metrc)) {
       Ue default fnt fr lkng up fnt metrc f the paed
       fnt  nt a bae fnt
      f (th.SerfFnt(name)) {
        lkupName = "Tme-Rman";
      } ele {
        lkupName = "Helvetca";
      }
    }
    cnt glyphWdth = Metrc[lkupName];
    f (Num(glyphWdth)) {
      defaultWdth = glyphWdth;
      mnpace = true;
    } ele {
      wdth = glyphWdth();  expand lazy wdth array
    }
    return {