Revert "Use static for closure."

This reverts commit cec16c6.

tests/phpunit/tests/fonts/font-library/wpFontsDir.php

@@ -81,7 +81,7 @@ public function test_fonts_dir_filters_do_not_trigger_infinite_loop() {
 
 		add_filter(
 			'upload_dir',
-			static function ( $upload_dir ) {
+			function ( $upload_dir ) {
 				static $count = 0;
 				++$count;
 				// It may be hit a couple of times, at five iterations assume an infinite loop.