Description:
------------
When class variables refers to a constant of the class using self::, get_class_vars produces a fatal error. 

Note that the code works if I access the class previously (uncomment commented lines in reproduction)

Reproduce code:
---------------
<?php
class foo {
        const FOO = 1;
        public $x = self::FOO;
}

//$b = new foo();
//var_dump($b);
var_dump(get_class_vars("foo"));


Expected result:
----------------
array(1) {
  ["x"]=>
  int(1)
}


Actual result:
--------------
Fatal error: Cannot access self:: when no class scope is active in /root/const2.php on line 9