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(loadingTask).toEqual(data[1].loadingTask);
      await loadingTask.destroy();
    });
    it("creates pdf doc from URL and aborts before worker initialized", async function () {
      const loadingTask = getDocument(basicApiGetDocumentParams);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      const destroyed = loadingTask.destroy();
      try {
        await loadingTask.promise;
        
        expect(false).toEqual(true);
      } catch (reason) {
        expect(true).toEqual(true);
        await destroyed;
      }
    });
    it("creates pdf doc from URL and aborts loading after worker initialized", async function () {
      const loadingTask = getDocument(basicApiGetDocumentParams);
      expect(loadingTask instanceof PDFDocumentLoadingTask).toEqual(true);
      
      
      const destroyed = loadingTask._worker.promise.then(function () {
        return loadingTask.destroy();
      });
      await destroyed;
      expect(true).toEqual(true);
    });
    it("creates pdf doc from typed array", async function () {
      const typedArrayPdf = await DefaultFileReaderFactory.fetch({
        path: TEST_PDFS_PATH + basicApiFileName,