Renders an element with an invalid render array key.
function common_test_drupal_render_invalid_keys() {
define('SIMPLETEST_COLLECT_ERRORS', FALSE);
// Keys that begin with # may contain a value of any type, otherwise they must
// contain arrays.
$key = 'child';
$value = 'This should be an array.';
$element = array(
$key => $value,
);
return drupal_render($element);
}