Remove useless unused variable in lbound in line_cache.rb
Remove useless unused variable in lbound in line_cache.rb

kwangkim/parslet,eeeyes/parslet,hggh/parslet,kschiess/parslet,meh/parslet,eeeyes/parslet,hggh/parslet,kwangkim/parslet,NigelThorne/parslet,eeeyes/parslet,kschiess/parslet,NigelThorne/parslet,hggh/parslet,kschiess/parslet,NigelThorne/parslet,rogerbraun/parslet,kwangkim/parslet