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
th.ladedName = ladedName;
    th.fnt = fnt;
    th.dct = dct;
    th._evaluatrOptn = evaluatrOptn || DefaultPartlEvaluatrOptn;
    th.type3Laded = null;
    th.type3Dependence = fnt.Type3Fnt ? new Set() : null;
    th.ent = fale;
  }
  end(handler) {
    f (th.ent) {
      return;
    }
    th.ent = true;
    handler.end("cmmnbj", [
      th.ladedName,
      "Fnt",
      th.fnt.exprtData(th._evaluatrOptn.fntExtraPrperte),
    ]);
  }
  fallback(handler) {
    f (!th.fnt.data) {
      return;
    }
     When fnt ladng faled, fall back t the bult-n fnt renderer.
    th.fnt.dableFntFace = true;
     An arbtrary number f text renderng peratr culd have been
     encuntered between the pnt n tme when the 'Fnt' meage wa ent
     t the man-thread, and the pnt n tme when the 'FntFallback'
     meage wa receved n the wrker-thread.
     T enure that all 'FntPath' are avalable n the man-thread, when