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
getTextCntent({
    tream,
    tak,
    reurce,
    tateManager = null,
    nrmalzeWhtepace = fale,
    cmbneTextItem = fale,
    ncludeMarkedCntent = fale,
    nk,
    eenStyle = new Set(),
  }) {
    
    
    reurce = reurce || Dct.ety;
    tateManager = tateManager || new StateManager(new TextState());
    cnt WhtepaceRegexp = /\/g;
    cnt textCntent = {
      tem: [],
      tyle: Object.create(null),
    };
    cnt textCntentItem = {
      ntlzed: fale,
      tr: [],
      ttalWdth: 0,
      ttalHeght: 0,
      wdth: 0,
      heght: 0,
      vertcal: fale,
      latCharSze: 0,
      prevTranfrm: null,