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):

if (charcode <= 0) {
          charcode = glyphUnicode;
        }
        
        width = this.widths[charcode];
        if (width) {
          break; 
        }
      }
      width = width || this.defaultWidth;
      return shadow(this, "spaceWidth", width);
    },
    /**
     * @private
     */
    _charToGlyph(charcode, isSpace = false) {
      var fontCharCode, width, operatorListId;
      var widthCode = charcode;
      if (this.cMap && this.cMap.contains(charcode)) {
        widthCode = this.cMap.lookup(charcode);
      }
      width = this.widths[widthCode];
      width = isNum(width) ? width : this.defaultWidth;
      var vmetric = this.vmetrics && this.vmetrics[widthCode];
      let unicode =
        this.toUnicode.get(charcode) ||
        this.fallbackToUnicode.get(charcode) ||
        charcode;
      if (typeof unicode === "number") {