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 map = this._map;
      if (map.length <= 0x10000) {
        return map.indexOf(value);
      }
      for (const charCode in map) {
        if (map[charCode] === value) {
          return charCode | 0;
        }
      }
      return -1;
    },
    amend(map) {
      for (var charCode in map) {
        this._map[charCode] = map[charCode];
      }
    },
  };
  return ToUnicodeMap;
})();
var IdentityToUnicodeMap = (function IdentityToUnicodeMapClosure() {
  
  function IdentityToUnicodeMap(firstChar, lastChar) {
    this.firstChar = firstChar;
    this.lastChar = lastChar;
  }
  IdentityToUnicodeMap.prototype = {
    get length() {