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(reason instanceof InvalidPDFException).toEqual(true);
        expect(reason.message).toEqual(
          "The PDF file is empty, i.e. its size is zero bytes."
        );
      }
      await loadingTask.destroy();
    });
    it("checks that `docId`s are unique and increasing", async function () {
      const loadingTask1 = getDocument(basicApiGetDocumentParams);
      expect(loadingTask1 instanceof PDFDocumentLoadingTask).toEqual(true);
      await loadingTask1.promise;
      const docId1 = loadingTask1.docId;
      const loadingTask2 = getDocument(basicApiGetDocumentParams);
      expect(loadingTask2 instanceof PDFDocumentLoadingTask).toEqual(true);
      await loadingTask2.promise;
      const docId2 = loadingTask2.docId;
      expect(docId1).not.toEqual(docId2);
      const docIdRegExp = /^d(\d+)$/,
        docNum1 = docIdRegExp.exec(docId1)?.[1],
        docNum2 = docIdRegExp.exec(docId2)?.[1];
      expect(+docNum1).toBeLessThan(+docNum2);
      await Promise.all([loadingTask1.destroy(), loadingTask2.destroy()]);
    });
  });
  describe("PDFWorker", function () {
    it("worker created or destroyed", async function () {
      if (isNodeJS) {
        pending("Worker is not supported in Node.js.");
      }
      const worker = new PDFWorker({ name: "test1" });