Coding Standards: Use static closures when not using $this.

When a closure does not use `$this`, it can be made `static` for improved performance.

Static closures are supported in PHP since PHP 5.4. ​

Props jrf, hellofromTonya, swissspidy, SergeyBiryukov.
See #53359.

git-svn-id: https://develop.svn.wordpress.org/trunk@51657 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -2692,7 +2692,7 @@ function wp_maybe_inline_styles() {
 		// Reorder styles array based on size.
 		usort(
 			$styles,
-			function( $a, $b ) {
+			static function( $a, $b ) {
 				return ( $a['size'] <= $b['size'] ) ? -1 : 1;
 			}
 		);