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
Object.assign(styleCache, value.styles);
          this._processItems(value.items, styleCache);
          pump();
        }, capability.reject);
      };
      this._reader = this._textContentStream.getReader();
      pump();
    } else {
      throw new Error(
        'Neither "textContent" nor "textContentStream" parameters specified.'
      );
    }
    capability.promise.then(() => {
      styleCache = null;
      if (!timeout) {
        
        render(this);
      } else {
        
        this._renderTimer = setTimeout(() => {
          render(this);
          this._renderTimer = null;
        }, timeout);
      }
    }, this._capability.reject);
  }
  /**
   * @param {boolean} [expandDivs]
   */
  expandTextDivs(expandDivs = false) {