Incorrect `no block given` message with new

``` ruby
class Person
  property :name, :age

  def initialize(@name = nil, @age = nil)
    yield self
  end
end

person = Person.new do |p|
  p.name = "Jacob"
  p.age = "25"
end
```

Incorrectly complains:

```
Error in /Users/asterite-manas/Projects/crystal/coco.cr:13: no block given

person = Person.new do |p|
                ^~~
```
