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(viewport.transform).toEqual([1, 0, 0, -1, 100, 741.89]);
    });
    it('gets viewport respecting "dontFlip" argument', function () {
      const scale = 1,
        rotation = 0;
      const viewport = page.getViewport({ scale, rotation });
      const dontFlipViewport = page.getViewport({
        scale,
        rotation,
        dontFlip: true,
      });
      expect(dontFlipViewport).not.toEqual(viewport);
      expect(dontFlipViewport).toEqual(viewport.clone({ dontFlip: true }));
      expect(viewport.transform).toEqual([1, 0, 0, -1, 0, 841.89]);
      expect(dontFlipViewport.transform).toEqual([1, 0, -0, 1, 0, 0]);
    });
    it("gets viewport with invalid rotation", function () {
      expect(function () {
        page.getViewport({ scale: 1, rotation: 45 });
      }).toThrow(
        new Error(
          "PageViewport: Invalid rotation, must be a multiple of 90 degrees."
        )
      );
    });
    it("gets annotations", async function () {
      const defaultPromise = page.getAnnotations().then(function (data) {
        expect(data.length).toEqual(4);
      });
      const anyPromise = page