Added Ruby::Node#if_false

lib/oga/ruby/node.rb

@@ -148,6 +148,15 @@ module Oga
         Node.new(:if, [self, yield])
       end
 
+      ##
+      # Wraps the current node in an `if !...` statement.
+      #
+      # @see [#if_true]
+      #
+      def if_false
+        self.not.if_true { yield }
+      end
+
       ##
       # Wraps the current node in a `while` statement.
       #