Range with excluding and float while calling rand causes TypeError: cannot exclude non Integer end value

No issue under MRI.

To reproduce:
```ruby
rand(0...1.0)
```

Error:
```
TypeError: cannot exclude non Integer end value
	from (irb):2:in `max'
	from (irb):2:in `random_range'
	from (irb):2:in `random'
	from (irb):2:in `rand'
	from (irb):2
	from ~/.rubies/truffleruby-1.0.0-rc9/bin/irb:29:in `<main>'
```