Attach (recommended) or Link to PDF file here:
[Hong Kong Aircraft Engineering Company Limited_1511417616.1 2.pdf](https://github.com/mozilla/pdf.js/files/1539395/Hong.Kong.Aircraft.Engineering.Company.Limited_1511417616.1.2.pdf)


Configuration:
- Web browser and its version: Chrome: 63 
- Operating system and its version: windows and macOs
- PDF.js version: 2.0.185
- Is a browser extension: No

Steps to reproduce the problem:
1. Upload the above PDF and search for "article 1"
2. PDF.js showing only **2** match But actually **4** times available.   

What is the expected behavior? (add screenshot)

![screen shot 2017-12-07 at 7](https://user-images.githubusercontent.com/6101789/33720106-ed404576-db88-11e7-9c19-cf6aea74e9f3.png)



What went wrong? (add screenshot)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

used = horizon[k].boundary === affectedBoundary;
      }
      for (
        k = j + 1;
        !used && k < horizon.length && horizon[k].end <= affectedBoundary.y2;
        k++
      ) {
        used = horizon[k].boundary === affectedBoundary;
      }
      for (k = 0; !used && k < changedHorizon.length; k++) {
        used = changedHorizon[k].boundary === affectedBoundary;
      }
      if (!used) {
        affectedBoundary.x2New = maxXNew;
      }
    }
    Array.prototype.splice.apply(
      horizon,
      [i, j - i + 1].concat(changedHorizon)
    );
  }
  
  for (const horizonPart of horizon) {
    const affectedBoundary = horizonPart.boundary;
    if (affectedBoundary.x2New === undefined) {
      affectedBoundary.x2New = Math.max(width, affectedBoundary.x2);
    }
  }
}
class TextLayerRenderTask {