Coding Standards: Always use parentheses when instantiating an object.

Note: This will be enforced by WPCS 3.0.0.

Props jrf.
See #56791.

git-svn-id: https://develop.svn.wordpress.org/trunk@54891 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/functions.php

@@ -4302,7 +4302,7 @@ function _wp_json_sanity_check( $data, $depth ) {
 			}
 		}
 	} elseif ( is_object( $data ) ) {
-		$output = new stdClass;
+		$output = new stdClass();
 		foreach ( $data as $id => $el ) {
 			if ( is_string( $id ) ) {
 				$clean_id = _wp_json_convert_string( $id );