Fix input object printing

Author: rmosolgo

lib/graphql/language/nodes.rb

@@ -296,8 +296,6 @@ def serialize_value_for_hash(value)
               serialize_value_for_hash v
             end
           when Enum
-            # TODO: this is required for _loading_ default values for input objects,
-            # but it breaks printing those values!
             value.name
           when NullValue
             nil

lib/graphql/language/printer.rb

@@ -93,7 +93,7 @@ def print_inline_fragment(inline_fragment, indent: "")
       end
 
       def print_input_object(input_object)
-        print_node(input_object.to_h)
+        "{#{input_object.arguments.map { |a| "#{a.name}: #{print(a.value)}" }.join(", ")}}"
       end
 
       def print_list_type(list_type)