Attach (recommended) or Link to PDF file here:
[298865.pdf](https://github.com/mozilla/pdf.js/files/2753236/298865.pdf)


Configuration:
- Web browser and its version:chrome 71.0.3578.98
- Operating system and its version:mac os 10.12.6
- PDF.js version:I use online demo in github
- Is a browser extension:no

Steps to reproduce the problem:
1. search "中华" or "电力" or so on,the highlight position is not right

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/10000986/51087378-7eff5100-178d-11e9-991a-005d77b82f31.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/10000986/51087374-6ee77180-178d-11e9-9707-281924f95fd0.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):
https://mozilla.github.io/pdf.js/web/viewer.html
expect(outline).toEqual(null);
      await loadingTask.destroy();
    });
    it("gets outline", async function () {
      const outline = await pdfDocument.getOutline();
      
      expect(Array.isArray(outline)).toEqual(true);
      expect(outline.length).toEqual(2);
      
      const outlineItem = outline[1];
      expect(outlineItem.title).toEqual("Chapter 1");
      expect(Array.isArray(outlineItem.dest)).toEqual(true);
      expect(outlineItem.url).toEqual(null);
      expect(outlineItem.unsafeUrl).toBeUndefined();
      expect(outlineItem.newWindow).toBeUndefined();
      expect(outlineItem.bold).toEqual(true);
      expect(outlineItem.italic).toEqual(false);
      expect(outlineItem.color).toEqual(new Uint8ClampedArray([0, 64, 128]));
      expect(outlineItem.items.length).toEqual(1);
      expect(outlineItem.items[0].title).toEqual("Paragraph 1.1");
    });
    it("gets outline containing a URL", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("issue3214.pdf"));
      const pdfDoc = await loadingTask.promise;
      const outline = await pdfDoc.getOutline();
      expect(Array.isArray(outline)).toEqual(true);
      expect(outline.length).toEqual(5);
      const outlineItemTwo = outline[2];
      expect(typeof outlineItemTwo.title).toEqual("string");
      expect(outlineItemTwo.dest).toEqual(null);