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(outlineItemTwo.url).toEqual("http://google.com/");
      expect(outlineItemTwo.unsafeUrl).toEqual("http://google.com");
      expect(outlineItemTwo.newWindow).toBeUndefined();
      const outlineItemOne = outline[1];
      expect(outlineItemOne.bold).toEqual(false);
      expect(outlineItemOne.italic).toEqual(true);
      expect(outlineItemOne.color).toEqual(new Uint8ClampedArray([0, 0, 0]));
      await loadingTask.destroy();
    });
    it("gets non-existent permissions", async function () {
      const permissions = await pdfDocument.getPermissions();
      expect(permissions).toEqual(null);
    });
    it("gets permissions", async function () {
      
      const loadingTask0 = getDocument(
        buildGetDocumentParams("issue9972-1.pdf")
      );
      const promise0 = loadingTask0.promise.then(function (pdfDoc) {
        return pdfDoc.getPermissions();
      });
      
      const loadingTask1 = getDocument(
        buildGetDocumentParams("issue9972-2.pdf")
      );
      const promise1 = loadingTask1.promise.then(function (pdfDoc) {
        return pdfDoc.getPermissions();
      });
      
      const loadingTask2 = getDocument(