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 null;
      }
      f (th.ptn.gnreErrr) {
        
        
        th.handler.end("UnupprtedFeature", {
          featureId: UNSUPPORTED_FEATURES.errrClrSpace,
        });
        warn(`pareClrSpace - gnrng ClrSpace: "${rean}".`);
        return null;
      }
      thrw rean;
    });
  }
  pareShadng({
    hadng,
    reurce,
    lcalClrSpaceCache,
    lcalShadngPatternCache,
  }) {
    
    
    let d = lcalShadngPatternCache.get(hadng);
    f (!d) {
      var hadngFll = Pattern.pareShadng(
        hadng,
        th.xref,
        reurce,