Add shadowarg to node list

lib/mutant.rb

@@ -42,6 +42,7 @@ module Parser
         and not or if when case while until while_post
         until_post for break next redo return resbody
         kwbegin begin retry preexe postexe iflipflop eflipflop
+        shadowarg
       ).map(&:to_sym).to_set.freeze
   end # Meta
 end # Parser

lib/mutant/mutator/node/generic.rb

@@ -16,7 +16,8 @@ module Mutant
           :kwrestarg, :kwoptarg, :kwarg, :undef, :module, :empty,
           :alias, :for, :xstr, :back_ref, :class,
           :sclass, :match_with_lvasgn, :match_current_line, :while_post,
-          :until_post, :preexe, :postexe, :iflipflop, :eflipflop, :kwsplat
+          :until_post, :preexe, :postexe, :iflipflop, :eflipflop, :kwsplat,
+          :shadowarg
         )
 
       private