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):

for (let i = 0, len = items.length; i < len; i++) {
      if (items[i].str === undefined) {
        if (
          items[i].type === "beginMarkedContentProps" ||
          items[i].type === "beginMarkedContent"
        ) {
          const parent = this._container;
          this._container = document.createElement("span");
          this._container.classList.add("markedContent");
          if (items[i].id !== null) {
            this._container.setAttribute("id", `${items[i].id}`);
          }
          parent.appendChild(this._container);
        } else if (items[i].type === "endMarkedContent") {
          this._container = this._container.parentNode;
        }
        continue;
      }
      this._textContentItemsStr.push(items[i].str);
      appendText(this, items[i], styleCache, this._layoutTextCtx);
    }
  }
  /**
   * @private
   */
  _layoutText(textDiv) {