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(
        worker1.port !== worker2.port &&
          worker1.port !== worker3.port &&
          worker2.port !== worker3.port
      ).toEqual(true);
      worker1.destroy();
      worker2.destroy();
      worker3.destroy();
    });
    it("gets current workerSrc", function () {
      if (isNodeJS) {
        pending("Worker is not supported in Node.js.");
      }
      const workerSrc = PDFWorker.workerSrc;
      expect(typeof workerSrc).toEqual("string");
      expect(workerSrc).toEqual(GlobalWorkerOptions.workerSrc);
    });
  });
  describe("PDFDocument", function () {
    let pdfLoadingTask, pdfDocument;
    beforeAll(async function () {
      pdfLoadingTask = getDocument(basicApiGetDocumentParams);
      pdfDocument = await pdfLoadingTask.promise;
    });
    afterAll(async function () {
      await pdfLoadingTask.destroy();
    });
    it("gets number of pages", function () {
      expect(pdfDocument.numPages).toEqual(3);
    });