[ruby/json] Delete code that is based on CVTUTF
I did this based on manual inspection, comparing the code to my re-created history of CVTUTF at https://git.lukeshu.com/2git/cvtutf/ (created by the scripts at https://git.lukeshu.com/2git/cvtutf-make/)
https://github.com/ruby/json/commit/0819553144
[ruby/json] Delete code that is based on CVTUTF
I did this based on manual inspection, comparing the code to my re-created
history of CVTUTF at https://git.lukeshu.com/2git/cvtutf/ (created by the
scripts at https://git.lukeshu.com/2git/cvtutf-make/)
https://github.com/ruby/json/commit/0819553144