Revert "[EXPERIMENTAL] Make Symbol#to_s return a frozen String [Feature #16150]"
Revert "[EXPERIMENTAL] Make Symbol#to_s return a frozen String [Feature #16150]"

This reverts commit 6ffc045a817fbdf04a6945d3c260b55b0fa1fd1e.

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