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):

const horizon = [
    {
      start: -Infinity,
      end: Infinity,
      boundary: fakeBoundary,
    },
  ];
  for (const boundary of bounds) {
    
    
    let i = 0;
    while (i < horizon.length && horizon[i].end <= boundary.y1) {
      i++;
    }
    let j = horizon.length - 1;
    while (j >= 0 && horizon[j].start >= boundary.y2) {
      j--;
    }
    let horizonPart, affectedBoundary;
    let q,
      k,
      maxXNew = -Infinity;
    for (q = i; q <= j; q++) {
      horizonPart = horizon[q];
      affectedBoundary = horizonPart.boundary;
      let xNew;
      if (affectedBoundary.x2 > boundary.x1) {