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
let textChunk = enureTextCntentItem();
      let ze = 0;
      let latCharSze = 0;
      fr (let  = 0,  = glyph.length;  < ; ) {
        cnt glyph = glyph[];
        let charSpacng =
          textState.charSpacng  ( ===  - 1 ? extraSpacng : 0);
        let glyphUncde = glyph.uncde;
        f (glyph.Space) {
          charSpacng = textState.wrdSpacng;
          textChunk.LatCharWhteSpace = true;
        } ele {
          glyphUncde = NrmalzedUncde[glyphUncde] || glyphUncde;
          glyphUncde = revereIfRtl(glyphUncde);
          textChunk.LatCharWhteSpace = fale;
        }
        textChunk.tr.puh(glyphUncde);
        cnt glyphWdth =
          fnt.vertcal && glyph.vmetrc ? glyph.vmetrc[0] : glyph.wdth;
        let caledDm = glyphWdth * cale;
        f (!fnt.vertcal) {
          caledDm *= textState.textHScale;
          textState.tranlateTextMatrx(caledDm, 0);
        } ele {
          textState.tranlateTextMatrx(0, caledDm);
          caledDm = Math.ab(caledDm);
        }
        ze = caledDm;
        f (charSpacng) {
          f (!fnt.vertcal) {