Description:
------------
If the first property of a class is private and an instance of that class is wrapped by ArrayIterator, that first private property may be exposed by ArrayIterator::current() and ArrayIterator::key(). Specifically, this occurs when: 
 - current() and key() are called right after obtaining the iterator from ArrayObject::getIterator(), OR
 - current() and key() are called right after the iterator position was reset due to the current position becoming invalid.

In the reproduce code below, notice how the iterator behaves differently depending on how it was returned to its starting position.

This issue affects snaps from 5_2, 5_3 and HEAD.
It can be fixed with some extra calls to spl_array_skip_protected() in spl_array.c.
Proposed patch against 5_3: http://pastebin.ca/1081771


Reproduce code:
---------------
<?php
class C {
	private $priv1 = 'secret1';
	private $priv2 = 'secret2';
	public $pub1 = 'public1';
	public $pub2 = 'public2';
	public $pub3 = 'public3';
} 

function showFirstTwoItems($it) {
  echo str_replace("\0", '\0', $it->key()) . " => " . $it->current() . "\n";
  $it->next();
  echo str_replace("\0", '\0', $it->key()) . " => " . $it->current() . "\n";
}

$ao = new ArrayObject(new C);
$ai = $ao->getIterator();

echo "--> Show the first two items:\n";
showFirstTwoItems($ai);

echo "\n--> Rewind and show the first two items:\n";
$ai->rewind();
showFirstTwoItems($ai);

echo "\n--> Invalidate current position and show the first two items:\n";
unset($ai[$ai->key()]);
$ai->current();
showFirstTwoItems($ai);
?>

Expected result:
----------------
--> Show the first two items:
pub1 => public1
pub2 => public2

--> Rewind and show the first two items:
pub1 => public1
pub2 => public2

--> Invalidate current position and show the first two items:
pub1 => public1
pub3 => public3

Actual result:
--------------
--> Show the first two items:
\0C\0priv1 => secret1
pub1 => public1

--> Rewind and show the first two items:
pub1 => public1
pub2 => public2

--> Invalidate current position and show the first two items:
\0C\0priv1 => secret1
pub1 => public1