parse.y: check NTH_REF range
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50671 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
parse.y: check NTH_REF range
nil.
[ruby-core:69393] [Bug #11192]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50671 b2dd03c8-39d4-4d8f-98ff-823fe69b080e