iseq.c: narrow down protected region
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53282 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
iseq.c: narrow down protected region
region, and check/convert/prepare arguments before setting
base_block which needs to roll back.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53282 b2dd03c8-39d4-4d8f-98ff-823fe69b080e