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):

expect(stringToPDFString(str3)).toEqual("");
    });
  });
  describe("removeNullCharacters", function () {
    it("should not modify string without null characters", function () {
      const str = "string without null chars";
      expect(removeNullCharacters(str)).toEqual("string without null chars");
    });
    it("should modify string with null characters", function () {
      const str = "string\x00With\x00Null\x00Chars";
      expect(removeNullCharacters(str)).toEqual("stringWithNullChars");
    });
  });
  describe("ReadableStream", function () {
    it("should return an Object", function () {
      const readable = new ReadableStream();
      expect(typeof readable).toEqual("object");
    });
    it("should have property getReader", function () {
      const readable = new ReadableStream();
      expect(typeof readable.getReader).toEqual("function");
    });
  });
  describe("URL", function () {
    it("should return an Object", function () {
      const url = new URL("https://example.com");
      expect(typeof url).toEqual("object");
    });
    it("should have property `href`", function () {
      const url = new URL("https://example.com");