File sizes in xlsx-js-style are large compared to others

[Fmstrat]

Different forks of SheetJS output different file sizes, and xlsx-js-style suffers from the large file size issue.

This has been reported upstream here: SheetJS#520 (comment)

In that particular comment, they believe it may be a font issue, however if so the font is getting embedded repeatedly due to the exponential runaway file size.

As a test, I:

• Took a 5.9MB XLSX file
• Opened it with xlsx-js-style and wrote without compression: 81.9MB
• Opened it with xlsx-js-style and wrote with compression: 17.8MB
• Open either of the above two files with OnlyOffice, save, and it's back down to 5.9MB

Even with compression, this seems to be an issue.