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
) {
          passwordNeededCapability.resolve();
          updatePassword("qwerty"); 
          return;
        }
        if (
          reason === PasswordResponses.INCORRECT_PASSWORD &&
          !passwordIncorrectCapability.settled
        ) {
          passwordIncorrectCapability.resolve();
          updatePassword("asdfasdf"); 
          return;
        }
        
        expect(false).toEqual(true);
      };
      const data = await Promise.all([
        passwordNeededCapability.promise,
        passwordIncorrectCapability.promise,
        loadingTask.promise,
      ]);
      expect(data[2] instanceof PDFDocumentProxy).toEqual(true);
      await loadingTask.destroy();
    });
    it("creates pdf doc from PDF file protected with only a user password", async function () {
      const filename = "pr6531_2.pdf";
      const passwordNeededLoadingTask = getDocument(
        buildGetDocumentParams(filename, {
          password: "",
        })