Description:
------------
str_replace and str_ireplace cause a memory leak

Reproduce code:
---------------
$chars_ph = array('-');
$chars_rep = array('045]');
$subject = 'Programmable 15-Bar Pump-Espresso Coffee Machine';
$i = 0;

do {
$subject = str_replace($chars_rep, $subject);
++$i;
}
while ($i<100000);

Actual result:
--------------
Php script execution stops after exceeding php memory pool.