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
it("gets fingerprints", function () {
      expect(pdfDocument.fingerprints).toEqual([
        "ea8b35919d6279a369e835bde778611b",
        null,
      ]);
    });
    it("gets fingerprints, from modified document", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("annotation-tx.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      expect(pdfDoc.fingerprints).toEqual([
        "3ebd77c320274649a68f10dbf3b9f882",
        "e7087346aa4b4ae0911c1f1643b57345",
      ]);
      await loadingTask.destroy();
    });
    it("gets page", async function () {
      const data = await pdfDocument.getPage(1);
      expect(data instanceof PDFPageProxy).toEqual(true);
      expect(data.pageNumber).toEqual(1);
    });
    it("gets non-existent page", async function () {
      let outOfRangePromise = pdfDocument.getPage(100);
      let nonIntegerPromise = pdfDocument.getPage(2.5);
      let nonNumberPromise = pdfDocument.getPage("1");
      outOfRangePromise = outOfRangePromise.then(
        function () {
          throw new Error("shall fail for out-of-range pageNumber parameter");
        },