Description:
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Not actually sure which parts of this are actually supposed to work (as we didn't previously support by-ref modification for ArrayAccess).

Test script:
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<?php error_reporting(E_ALL);

class RefArray implements ArrayAccess {
    public $array;
    public function &offsetGet($key) { return $this->array[$key]; }
    public function offsetSet($key, $value) { $this->array[$key] = $value; }
    public function offsetExists($key) { return isset($this->array[$key]); }
    public function offsetUnset($key) { unset($this->array[$key]); }
}

$arr = new RefArray;
$arr[0] = 'abc';
$arr[1] =& $arr[0];