Description:
------------
PHP breaks OOB by not accepting null as a proper value for type_hinted argument.

In every OO language i know i have the way to dereference non-primitive object to null. Without this, i have to make _very_ big mess in code to make such things work.

Reproduce code:
---------------
class Foo {
}

function x(Foo $a, Foo $x) {
}

$l = new Foo();

x(null, $l);

Expected result:
----------------
normal work

Actual result:
--------------
Fatal error: Argument 1 must not be null in file.php in line 7