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):

mappings: [],
          hasShortCmap: false,
        };
      }
      let segment;
      let start = (file.start ? file.start : 0) + cmap.offset;
      file.pos = start;
      file.skip(2); 
      const numTables = file.getUint16();
      let potentialTable;
      let canBreak = false;
      
      
      
      
      
      
      for (let i = 0; i < numTables; i++) {
        const platformId = file.getUint16();
        const encodingId = file.getUint16();
        const offset = file.getInt32() >>> 0;
        let useTable = false;
        
        
        if (
          potentialTable &&
          potentialTable.platformId === platformId &&
          potentialTable.encodingId === encodingId
        ) {
          continue;