Enumerable#chunk without passing a block is supported since Ruby 2.4

MRI (2.5.3)

```ruby
[1,2,3,4,5].chunk
# => #<Enumerator: [1, 2, 3, 4, 5]:chunk>
```

TruffleRuby (1.0.0-rc10)

Error:

```
[1,2,3,4,5].chunk
ArgumentError: no block given
	from (irb):16:in `chunk'
	from (irb):16
	from ~/.rubies/truffleruby-1.0.0-rc10/bin/irb:29:in `<main>'
```
