[ruby/io-nonblock] Revert "Remove usage of IO internals."
This reverts commit https://github.com/ruby/io-nonblock/commit/9772b6dcb63c.
https://github.com/ruby/io-nonblock/commit/08cabf78e1
[ruby/io-nonblock] Revert "Remove usage of IO internals."
This reverts commit https://github.com/ruby/io-nonblock/commit/9772b6dcb63c.
https://github.com/ruby/io-nonblock/commit/08cabf78e1