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 capability = createPromiseCapability();
    let styleCache = Object.create(null);
    
    const canvas = this._document.createElement("canvas");
    canvas.height = canvas.width = DEFAULT_FONT_SIZE;
    if (
      typeof PDFJSDev === "undefined" ||
      PDFJSDev.test("MOZCENTRAL || GENERIC")
    ) {
      canvas.mozOpaque = true;
    }
    this._layoutTextCtx = canvas.getContext("2d", { alpha: false });
    if (this._textContent) {
      const textItems = this._textContent.items;
      const textStyles = this._textContent.styles;
      this._processItems(textItems, textStyles);
      capability.resolve();
    } else if (this._textContentStream) {
      const pump = () => {
        this._reader.read().then(({ value, done }) => {
          if (done) {
            capability.resolve();
            return;
          }