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):

expect(opListAnnotEnable.lastChunk).toEqual(true);
      const opListAnnotEnableForms = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE_FORMS,
      });
      expect(opListAnnotEnableForms.fnArray.length).toBeGreaterThan(40);
      expect(opListAnnotEnableForms.argsArray.length).toBeGreaterThan(40);
      expect(opListAnnotEnableForms.lastChunk).toEqual(true);
      const opListAnnotEnableStorage = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE_STORAGE,
      });
      expect(opListAnnotEnableStorage.fnArray.length).toBeGreaterThan(170);
      expect(opListAnnotEnableStorage.argsArray.length).toBeGreaterThan(170);
      expect(opListAnnotEnableStorage.lastChunk).toEqual(true);
      
      expect(opListAnnotDisable.fnArray.length).toBeLessThan(
        opListAnnotEnableForms.fnArray.length
      );
      expect(opListAnnotEnableForms.fnArray.length).toBeLessThan(
        opListAnnotEnable.fnArray.length
      );
      expect(opListAnnotEnable.fnArray.length).toBeLessThan(
        opListAnnotEnableStorage.fnArray.length
      );
      await loadingTask.destroy();
    });
    it("gets document stats after parsing page", async function () {
      const stats = await page.getOperatorList().then(function () {
        return pdfDocument.getStats();
      });
      const expectedStreamTypes = {};