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
const pageMode = await pdfDoc.getPageMode();
      expect(pageMode).toEqual("UseNone");
      await loadingTask.destroy();
    });
    it("gets non-default page mode", async function () {
      const pageMode = await pdfDocument.getPageMode();
      expect(pageMode).toEqual("UseOutlines");
    });
    it("gets default viewer preferences", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const prefs = await pdfDoc.getViewerPreferences();
      expect(prefs).toEqual(null);
      await loadingTask.destroy();
    });
    it("gets non-default viewer preferences", async function () {
      const prefs = await pdfDocument.getViewerPreferences();
      expect(prefs).toEqual({ Direction: "L2R" });
    });
    it("gets default open action", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const openAction = await pdfDoc.getOpenAction();
      expect(openAction).toEqual(null);
      await loadingTask.destroy();
    });