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):

segment = segments[segIndex];
            start = segment.start;
            var end = segment.end;
            var delta = segment.delta;
            offsetIndex = segment.offsetIndex;
            for (j = start; j <= end; j++) {
              if (j === 0xffff) {
                continue;
              }
              glyphId = offsetIndex < 0 ? j : offsets[offsetIndex + j - start];
              glyphId = (glyphId + delta) & 0xffff;
              mappings.push({
                charCode: j,
                glyphId,
              });
            }
          }
        } else if (format === 6) {
          
          
          
          
          
          var firstCode = file.getUint16();
          var entryCount = file.getUint16();
          for (j = 0; j < entryCount; j++) {
            glyphId = file.getUint16();
            var charCode = firstCode + j;
            mappings.push({
              charCode,