Description:
------------
mysqli_result->fetch_array() uses MYSQLI_ASSOC as default argument. Not MYSQLI_BOTH like Documentation claims.

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

$foo = $_mysqli->query('SELECT 1 AS bar');
$arr = $foo->fetch_array();

print_r($arr); 
// $arr contains only 'bar' key

?>

Expected result:
----------------
Array
(
    [bar] => 1
)

Actual result:
--------------
Array
(
    [0] => 1
    [bar] => 1
)