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
pending("Worker is not supported in Node.js.");
      }
      const worker = new PDFWorker({ name: "test1" });
      const loadingTask = getDocument(
        buildGetDocumentParams(basicApiFileName, {
          worker,
        })
      );
      loadingTask.promise.then(function () {
        const docWorker = loadingTask._worker;
        expect(!!docWorker).toEqual(false);
        
        const messageHandlerPort = loadingTask._transport.messageHandler.comObj;
        expect(messageHandlerPort === worker.port).toEqual(true);
      });
      const destroyPromise = loadingTask.promise.then(function () {
        return loadingTask.destroy();
      });
      await destroyPromise;
      expect(worker.destroyed).toEqual(false);
      worker.destroy();
    });
    it("creates more than one worker", async function () {
      if (isNodeJS) {
        pending("Worker is not supported in Node.js.");
      }
      const worker1 = new PDFWorker({ name: "test1" });
      const worker2 = new PDFWorker({ name: "test2" });
      const worker3 = new PDFWorker({ name: "test3" });
      await Promise.all([worker1.promise, worker2.promise, worker3.promise]);