Description:
------------
When calling isset()/empty() on an object which uses overloading (__set()/__get()) the property state is not returned correctly. It just checks for real properties, but not overloaded once.

Reproduce code:
---------------
class foo {

  function __get ( $key, $val ) {
    /* code */
  }

}

$bar = new foo();
$bar->bak = 'bla';
var_dump(isset($bar->bak));

Expected result:
----------------
true

Actual result:
--------------
false