remove FieldDef

and on_field_def , :field_def and fixed all related tests
local variables will have to be determined outside the typed layer

lib/typed/tree/assignment.rb

@@ -6,9 +6,5 @@ module Typed
         @name , @value = n , v
       end
     end
-
-    class FieldDef < Statement
-      attr_accessor :name , :type , :value
-    end
   end
 end

lib/typed/tree/to_code.rb

@@ -40,15 +40,6 @@ module Typed
       params
     end
 
-    def on_field_def statement
-      type , name , value = *statement
-      w = Tree::FieldDef.new()
-      w.type = type
-      w.name = process(name)
-      w.value = process(value) if value
-      w
-    end
-
     def on_while_statement statement
       branch_type , condition , statements = *statement
       w = Tree::WhileStatement.new()