Coding Standards: Fix the Squiz.PHP.DisallowMultipleAssignments violations in wp-admin.

See #47632.


Built from https://develop.svn.wordpress.org/trunk@45583


git-svn-id: http://core.svn.wordpress.org/trunk@45394 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-screen.php

@@ -202,7 +202,8 @@ final class WP_Screen {
 			return $hook_name;
 		}
 
-		$post_type       = $taxonomy = null;
+		$post_type       = null;
+		$taxonomy        = null;
 		$in_admin        = false;
 		$action          = '';
 		$is_block_editor = false;
@@ -1015,7 +1016,10 @@ final class WP_Screen {
 			)
 		);
 
-		$wrapper_start = $wrapper_end = $form_start = $form_end = '';
+		$wrapper_start = '';
+		$wrapper_end   = '';
+		$form_start    = '';
+		$form_end      = '';
 
 		// Output optional wrapper.
 		if ( $options['wrap'] ) {