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 pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(1);
      const operatorList = await pdfPage.getOperatorList();
      expect(operatorList.fnArray.length).toBeGreaterThan(20);
      expect(operatorList.argsArray.length).toBeGreaterThan(20);
      expect(operatorList.lastChunk).toEqual(true);
      
      
      expect(operatorList.fnArray.includes(OPS.beginAnnotation)).toEqual(true);
      expect(operatorList.fnArray.includes(OPS.endAnnotation)).toEqual(true);
      await loadingTask.destroy();
    });
    it("gets operator list, with `annotationMode`-option", async function () {
      const loadingTask = getDocument(buildGetDocumentParams("evaljs.pdf"));
      const pdfDoc = await loadingTask.promise;
      const pdfPage = await pdfDoc.getPage(2);
      pdfDoc.annotationStorage.setValue("30R", { value: "test" });
      pdfDoc.annotationStorage.setValue("31R", { value: true });
      const opListAnnotDisable = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.DISABLE,
      });
      expect(opListAnnotDisable.fnArray.length).toEqual(0);
      expect(opListAnnotDisable.argsArray.length).toEqual(0);
      expect(opListAnnotDisable.lastChunk).toEqual(true);
      const opListAnnotEnable = await pdfPage.getOperatorList({
        annotationMode: AnnotationMode.ENABLE,
      });
      expect(opListAnnotEnable.fnArray.length).toBeGreaterThan(150);
      expect(opListAnnotEnable.argsArray.length).toBeGreaterThan(150);