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 docActions = await pdfDoc.getJSActions();
      const page1 = await pdfDoc.getPage(1);
      const page1Actions = await page1.getJSActions();
      const page3 = await pdfDoc.getPage(3);
      const page3Actions = await page3.getJSActions();
      expect(docActions).toEqual({
        DidPrint: [`this.getField("Text2").value = "DidPrint";`],
        DidSave: [`this.getField("Text2").value = "DidSave";`],
        WillClose: [`this.getField("Text1").value = "WillClose";`],
        WillPrint: [`this.getField("Text1").value = "WillPrint";`],
        WillSave: [`this.getField("Text1").value = "WillSave";`],
      });
      expect(page1Actions).toEqual({
        PageOpen: [`this.getField("Text1").value = "PageOpen 1";`],
        PageClose: [`this.getField("Text2").value = "PageClose 1";`],
      });
      expect(page3Actions).toEqual({
        PageOpen: [`this.getField("Text5").value = "PageOpen 3";`],
        PageClose: [`this.getField("Text6").value = "PageClose 3";`],
      });
      await loadingTask.destroy();
    });
    it("gets non-existent outline", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const outline = await pdfDoc.getOutline();