Description:
------------
If an abstract class attempts to access a class constant defined by its parent, a fatal error is issued.

Reproduce code:
---------------
<?php
abstract class A
{
	public function foo ()
	{
		echo $this->bar; //works
		echo self::BAR; //fatal error
	}
}

class B extends A
{
	public $bar = 'foovar';
	const BAR = 'fooconst';
}

$x = new B;
$x->foo();
?>

Expected result:
----------------
foovarfooconst

Actual result:
--------------
foovar
Fatal error: Undefined class constant 'BAR' in...