Description:
------------
If a closure has an argument and a used variable with the same name, PHP5 uses the 
variable; HHVM uses the argument.

The PHP5 behavior should be documented in the specification.

There's also an issue filed against HHVM to match PHP5's behavior (https://github.com/facebook/hhvm/issues/3406)

Test script:
---------------
<?php
$foo = 'used variable';
$closure = function ($foo) use ($foo) { return $foo; };

var_dump($closure('argument'));





Expected result:
----------------
'used variable'

Actual result:
--------------
PHP5: 'used variable'
HHVM: 'argument'