Attach (recommended) or Link to PDF file here:
https://www.nta.go.jp/taxes/tetsuzuki/shinsei/annai/joyaku/annai/pdf2/250.pdf

Configuration:
- Web browser and its version: Firefox 81.0a1
- Operating system and its version: Debian 5.6.7-1
- PDF.js version: latest in Firefox nightly
- Is a browser extension: No

Steps to reproduce the problem:
1. Open the pdf and paste the following text "本 店 又 は 主 た る 事 務 所 の 所 在 地" in "Full name" and in "Domicile and residence" textfields
2. Print or Save the pdf 

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/91207547-30f05480-e709-11ea-9abd-2af5d970dc46.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/91207663-69902e00-e709-11ea-8a1d-1ddd30cf0621.png)

Link to a viewer (if hosted on a site other than mozilla.github.io/pdf.js or as Firefox/Chrome extension):

const xref = new XRefMock([
        { ref: buttonWidgetRef, data: buttonWidgetDict },
      ]);
      AnnotationFactory.create(
        xref,
        buttonWidgetRef,
        pdfManagerMock,
        idFactoryMock
      ).then(({ data }) => {
        ta.annotationType).toEqual(AnnotationType.WIDGET);
        ta.checkBox).toEqual(false);
        ta.radioButton).toEqual(true);
        ta.fieldValue).toEqual("1");
        ta.buttonValue).toEqual("2");
        done();
      }, done.fail);
    });
    it("should handle radio buttons with a field value not an ascii string", function (done) {
      const parentDict = new Dict();
      parentDict.set("V", Name.get("\x91I=\x91\xf0\x93\xe0\x97e3"));
      const normalAppearanceStateDict = new Dict();
      normalAppearanceStateDict.set("\x91I=\x91\xf0\x93\xe0\x97e3", null);
      const appearanceStatesDict = new Dict();
      appearanceStatesDict.set("N", normalAppearanceStateDict);
      buttonWidgetDict.set("Ff", AnnotationFieldFlag.RADIO);
      buttonWidgetDict.set("Parent", parentDict);
      buttonWidgetDict.set("AP", appearanceStatesDict);
      const buttonWidgetRef = Ref.get(124, 0);
      const xref = new XRefMock([
        { ref: buttonWidgetRef, data: buttonWidgetDict },