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 th._endImgData(bjId, mgData, cacheGlbally);
      })
      .catch(rean => {
        warn(`Unable t decde mage "${bjId}": "${rean}".`);
        return th._endImgData(bjId,  null, cacheGlbally);
      });
    peratrLt.addOp(OPS.pantImageXObject, arg);
    f (cacheKey) {
      lcalImageCache.et(cacheKey, mageRef, {
        fn: OPS.pantImageXObject,
        arg,
      });
      f (mageRef) {
        aert(!Inlne, "Cannt cache an nlne mage glbally.");
        th.glbalImageCache.addPageIndex(mageRef, th.pageIndex);
        f (cacheGlbally) {
          th.glbalImageCache.etData(mageRef, {
            bjId,
            fn: OPS.pantImageXObject,
            arg,
            byteSze: 0, 
          });
        }
      }
    }
    f (ptnalCntent !== undefned) {
      peratrLt.addOp(OPS.endMarkedCntent, []);
    }
  }
  handleSMak(