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 data = await Promise.all([
        loadingTask1.promise,
        loadingTask2.promise,
      ]);
      const fingerprints1 = data[0].fingerprints;
      const fingerprints2 = data[1].fingerprints;
      expect(fingerprints1).not.toEqual(fingerprints2);
      expect(fingerprints1).toEqual(["2f695a83d6e7553c24fc08b7ac69712d", null]);
      expect(fingerprints2).toEqual(["04c7126b34a46b6d4d6e7a1eff7edcb6", null]);
      await Promise.all([loadingTask1.destroy(), loadingTask2.destroy()]);
    });
    it("write a value in an annotation, save the pdf and load it", async function () {
      let loadingTask = getDocument(buildGetDocumentParams("evaljs.pdf"));
      let pdfDoc = await loadingTask.promise;
      const value = "Hello World";
      pdfDoc.annotationStorage.setValue("55R", { value });
      const data = await pdfDoc.saveDocument();
      await loadingTask.destroy();
      loadingTask = getDocument(data);
      pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      const annotations = await pdfPage.getAnnotations();
      const field = annotations.find(annotation => annotation.id === "55R");
      expect(!!field).toEqual(true);
      expect(field.fieldValue).toEqual(value);
      await loadingTask.destroy();
    });
    describe("Cross-origin", function () {
      let loadingTask;
      function _checkCanLoad(expectSuccess, filename, options) {