* eval.c (rb_mod_refine, mod_using, top_using): don't show
  warnings because Refinements are no longer experimental.
  [ruby-core:55993] [Feature #8632]

* test/ruby/test_refinement.rb: related test.

* NEWS: fixes for the above change.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42272 b2dd03c8-39d4-4d8f-98ff-823fe69b080e