Forwardable breaks on private methods in ruby 2.4
Due to an optimization in r55376, attempting to forward to private methods no longer works in ruby 2.4. Among other things, this breaks haml template support in tilt. Example:
require 'forwardable' class Foo private def foo; :foo end extend Forwardable def_delegator :itself, :foo, :bar end p Foo.new.bar
On ruby 2.3, this outputs :foo, on 2.4.0preview2 it raises NoMethodError. I think r55376 should be reverted, as the optimization it uses does not appear to be able to handle private method calls.