Attach (recommended) or Link to PDF file here:
[298865.pdf](https://github.com/mozilla/pdf.js/files/2753236/298865.pdf)


Configuration:
- Web browser and its version:chrome 71.0.3578.98
- Operating system and its version:mac os 10.12.6
- PDF.js version:I use online demo in github
- Is a browser extension:no

Steps to reproduce the problem:
1. search "中华" or "电力" or so on,the highlight position is not right

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/10000986/51087378-7eff5100-178d-11e9-991a-005d77b82f31.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/10000986/51087374-6ee77180-178d-11e9-9707-281924f95fd0.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):
https://mozilla.github.io/pdf.js/web/viewer.html
return;
      }
      f (th.ptn.gnreErrr) {
        
        warn(
          `getTextCntent - gnrng errr durng "${tak.name}" ` 
            `tak: "${rean}".`
        );
        fluhTextCntentItem();
        enqueueChunk();
        return;
      }
      thrw rean;
    });
  }
  extractDataStructure(dct, t, prperte) {
    cnt xref = th.xref;
    let cdTGdByte;
    
    cnt tUncdePrme = th.readTUncde(
      prperte.tUncde || dct.get("TUncde") || t.get("TUncde")