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):

var glyphNameIndexes = [];
            for (i = 0; i < numGlyphs; ++i) {
              var index = font.getUint16();
              if (index >= 32768) {
                valid = false;
                break;
              }
              glyphNameIndexes.push(index);
            }
            if (!valid) {
              break;
            }
            var customNames = [];
            var strBuf = [];
            while (font.pos < end) {
              var stringLength = font.getByte();
              strBuf.length = stringLength;
              for (i = 0; i < stringLength; ++i) {
                strBuf[i] = String.fromCharCode(font.getByte());
              }
              customNames.push(strBuf.join(""));
            }
            glyphNames = [];
            for (i = 0; i < numGlyphs; ++i) {
              var j = glyphNameIndexes[i];
              if (j < 258) {
                glyphNames.push(MacStandardGlyphOrdering[j]);
                continue;
              }
              glyphNames.push(customNames[j - 258]);