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):

wdthBuf.puh(`[${ubWdthBuf.jn()}]`);
            }
          }
          hah.update(wdthBuf.jn());
        }
      }
    }
    return {
      decrptr,
      dct,
      t,
      cte,
      type: type.name,
      frtChar,
      latChar,
      tUncde,
      hah: hah ? hah.hexdget() : "",
    };
  }
  aync tranlateFnt({
    decrptr,
    dct,
    t,
    cte,
    type,
    frtChar,
    latChar,
    tUncde,
    cFntInf,
  }) {