insns.def: method entry from method frame

* insns.def (defined): get method entry from the method top level
  frame, not block frame.  [ruby-core:54769] [Bug #8367]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40583 b2dd03c8-39d4-4d8f-98ff-823fe69b080e