Description:
------------
You can cast to boolean using either (bool)$var or (boolean)$var. In scalar type hints currently only bool could be used which is inconsistent.

Test script:
---------------
<?php
$boolean = 1;
$boolean = (boolean) $boolean;


function dump_boolean(boolean $var)
{
    var_dump($var);
}

dump_boolean($boolean);

// https://3v4l.org/Cdtoe

Expected result:
----------------
I'd expect both boolean and bool work as scalar type hint because both work well for type casting.

Actual result:
--------------
https://3v4l.org/egb59