css.rb in sanitize-4.6.1

- old
+ new

@@ -253,10 +253,10 @@
     end
 
     return nil unless @config[:properties].include?(name)
 
     nodes          = prop[:children].dup
-    combined_value = ''
+    combined_value = String.new
 
     nodes.each do |child|
       value = child[:value]
 
       case child[:node]