should check whether a newly created method override a optimize
  method in case the method is defined in a prepended module of a
  built-in class.
  [ruby-core:72226] [Bug #11836]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53179 b2dd03c8-39d4-4d8f-98ff-823fe69b080e