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
this._textDivProperties = new WeakMap();
    this._renderingDone = false;
    this._canceled = false;
    this._capability = createPromiseCapability();
    this._renderTimer = null;
    this._bounds = [];
    
    this._capability.promise
      .finally(() => {
        if (!this._enhanceTextSelection) {
          
          this._textDivProperties = null;
        }
        if (this._layoutTextCtx) {
          
          
          this._layoutTextCtx.canvas.width = 0;
          this._layoutTextCtx.canvas.height = 0;
          this._layoutTextCtx = null;
        }
      })
      .catch(() => {
        
      });
  }
  /**
   * Promise for textLayer rendering task completion.
   * @type {Promise<void>}
   */
  get promise() {