Description:
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At PHP 5.23 ArrayObject::offsetUnset() works as I expected, but at PHP 5.24 it doesn't work as I expected. The array offset doesn't destroy/unset properly and it still reside in the array.

Reproduce code:
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$ArrayField = array("clip.clip_id", "clip.clip_title", "clip.clip_published_date", "media.media_name", "conditional_category.conditional_id", "conditional_category.conditional_name", "client_category_set.client_cids", "client_category_set.category_name");
$ArrayGroups = array("clip.clip_published_date",
"client_category_set.category_name", "clip.clip_title", "clip.clip_id");
$collection = new ArrayObject($ArrayField);
for ($iter = $collection->getIterator(); $iter->valid(); 
$iter->next()) {
  if (!in_array($iter->current(), $ArrayGroups)) {
    $collection->offsetUnset($iter->key());
  }
}



Expected result:
----------------
At PHP 5.22 & 5.23, the $arrayField at offset(3,4,5,6) get unset properly, but when I try this code at PHP 5.24 the $arrayField at those offsets didn't get unset as PHP 5.22/5.23 did.