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):

"defaultWidth",
  "descent",
  "fallbackName",
  "fontMatrix",
  "fontType",
  "isMonospace",
  "isSerifFont",
  "isType3Font",
  "italic",
  "loadedName",
  "mimetype",
  "missingFile",
  "name",
  "remeasure",
  "subtype",
  "type",
  "vertical",
];
const EXPORT_DATA_EXTRA_PROPERTIES = [
  "cMap",
  "defaultEncoding",
  "differences",
  "isSymbolicFont",
  "seacMap",
  "toFontChar",
  "toUnicode",
  "vmetrics",
  "widths",
];
function adjustWidths(properties) {