Description:
------------
dunno how to describe , simply put the code below on 4.3.4 / 4.3.5  gives (my) expected answer of '12'

on 5.0.0.b4 && RC2 the answer is '13' 
unsure which is the correct behaviour ;)

Reproduce code:
---------------
<?
  $word = 'Encyclopedia';
    $x = 0;
    while (!empty($word[$x])){
        $x++;
    }
    echo "The word <b>$word</b> has $x characters in it."; 
?>

Expected result:
----------------
The word Encyclopedia has 12 characters in it.

Actual result:
--------------
The word Encyclopedia has 13 characters in it.