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/theme.php

@@ -1331,7 +1331,7 @@ function _get_random_header_data() {
 		}
 
 		if ( empty( $headers ) ) {
-			return new stdClass;
+			return new stdClass();
 		}
 
 		$_wp_random_header = (object) $headers[ array_rand( $headers ) ];