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
cnt dfference = prperte.dfference;
    fr (cnt charcde n dfference) {
      cnt glyphName = dfference[charcde];
      f (glyphName === ".ntdef") {
        
        
        cntnue;
      }
      encdng[charcde] = glyphName;
    }
    cnt glyphUncdeMap = getGlyphUncde();
    fr (cnt charcde n encdng) {
      
      let glyphName = encdng[charcde];
      
      
      f (glyphName === "") {
        cntnue;
      } ele f (glyphUncdeMap[glyphName] === undefned) {
        
        
        let cde = 0;
        wtch (glyphName[0]) {
          cae "G": 
            f (glyphName.length === 3) {
              cde = pareInt(glyphName.ubtrng(1), 16);
            }
            break;
          cae "g": 
            f (glyphName.length === 5) {