Add more specs for `MatchData#begin` to handle `String` and `Symbol` arguments.
Add more specs for `MatchData#begin` to handle `String` and `Symbol` arguments.

ruby/spec,nobu/rubyspec,ruby/rubyspec,nobu/rubyspec,eregon/rubyspec,eregon/rubyspec,ruby/rubyspec,ruby/spec,eregon/rubyspec,ruby/spec,nobu/rubyspec