Description:
------------
I overrode the methods of ArrayObject to normalize the keys before setting and getting members. It appears that the overridden methods are skipped when modifying an array member.

Reproduce code:
---------------
<?php

class foo extends ArrayObject
{
    public function __construct($data = array(),
                                $flags = self::ARRAY_AS_PROPS,
                                $iterator = "ArrayIterator")
    {
        parent::__construct($data, $flags, $iterator);
    }

    public function offsetSet($key, $val)
    {
        echo "offsetSet invoked\n";
        parent::offsetSet($key, $val);
    }

    public function offsetGet($key)
    {
        echo "offsetGet invoked\n";
        return parent::offsetGet($key);
    }

}

$foo = new foo();

$foo->baz = array();
echo count($foo->baz) . "\n";

echo "---\n";

$foo->baz['bar'] = 'foo';
echo count($foo->baz) . "\n";


Expected result:
----------------
offsetSet invoked
offsetGet invoked
0
---
offsetGet invoked  --[*]
offsetSet invoked  _/
offsetGet invoked
1


[*] actually, I'm not sure exactly what output to expect here, but at least one of these I think should appear

Actual result:
--------------
offsetSet invoked
offsetGet invoked
0
---
offsetGet invoked
1