rubinius/rubinius — pull request #3020 by felix125 (2014-04-27 03:24:43+00:00)
Title: Rewrite String#tr_trans to improve the performance

- I had add a new private method tr_trans_ascii_only to deal with ascii only string.
- In order to get the best performance, I did not follow the DRY rule.
- I also add some benchmark. you can check them. https://gist.github.com/felix125/11235967
- Solve multiple char issue(#3015) as well