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 renderTask = pdfPage.render({
        canvasContext: canvasAndCtx.context,
        canvasFactory: CanvasFactory,
        viewport,
      });
      expect(renderTask instanceof RenderTask).toEqual(true);
      
      renderTask.onContinue = function (cont) {
        waitSome(cont);
      };
      try {
        await pdfDoc.cleanup();
        
        expect(false).toEqual(true);
      } catch (reason) {
        expect(reason instanceof Error).toEqual(true);
        expect(reason.message).toEqual(
          "startCleanup: Page 1 is currently rendering."
        );
      }
      await renderTask.promise;
      CanvasFactory.destroy(canvasAndCtx);
      await loadingTask.destroy();
    });
    it("caches image resources at the document/page level as expected (issue 11878)", async function () {
      const { NUM_PAGES_THRESHOLD } = GlobalImageCache,
        EXPECTED_WIDTH = 2550,
        EXPECTED_HEIGHT = 3300;
      const loadingTask = getDocument(buildGetDocumentParams("issue11878.pdf"));
      const pdfDoc = await loadingTask.promise;