Description:
------------
A callback function of array_filter in a class dosen't allow the use of $this.

Reproduce code:
---------------
class test {
	var $filter = '' //is a regex
	var $array; //has many values

	function test() {
		array_filter($array, array($this, 'filter'));
	}
	function filter( $value ) {
		return preg_match("/$this->filter/i", $value);
	}
}

Expected result:
----------------
The array should be filtered after the regex of the $this->filter value;

Actual result:
--------------
Fatal error:  Using $this when not in object context