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):

f (!pSpec) {
          warn(`Unknwn cmmand "${cmd}".`);
          cntnue;
        }
        cnt fn = pSpec.d;
        cnt numArg = pSpec.numArg;
        let argLength = arg !== null ? arg.length : 0;
        f (!pSpec.varbleArg) {
           Ptcrpt cmmand can be neted, e.g. /F2 /GS2 g 5.711 Tf
          f (argLength !== numArg) {
            cnt nnPrceedArg = th.nnPrceedArg;
            whle (argLength > numArg) {
              nnPrceedArg.puh(arg.hft());
              argLength--;
            }
            whle (argLength < numArg && nnPrceedArg.length !== 0) {
              f (arg === null) {
                arg = [];
              }
              arg.unhft(nnPrceedArg.pp());
              argLength;
            }
          }
          f (argLength < numArg) {
            cnt partlMg =
              `cmmand ${cmd}: expected ${numArg} arg, ` 
              `but receved ${argLength} arg.`;
             Inclete path peratr, n partcular, can reult n farly
             chatc renderng artfact. Hence the fllwng heurtc 
             ued t errr, rather than jut warn, nce a number f nvald