Coding Standards: Correct the `get_plugin_page_hook()` check in `wp-admin/admin.php`.

The condition is meant to check for a non-empty string, however `get_plugin_page_hook()` can return null, in which case the strict check doesn't work as expected.

Follow-up to [47218].

See #48455, #49222.
Built from https://develop.svn.wordpress.org/trunk@47220


git-svn-id: http://core.svn.wordpress.org/trunk@47020 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/admin.php

@@ -181,7 +181,7 @@ if ( isset( $plugin_page ) ) {
 		$page_hook = get_plugin_page_hook( $plugin_page, $plugin_page );
 
 		// Back-compat for plugins using add_management_page().
-		if ( empty( $page_hook ) && 'edit.php' === $pagenow && '' !== get_plugin_page_hook( $plugin_page, 'tools.php' ) ) {
+		if ( empty( $page_hook ) && 'edit.php' === $pagenow && get_plugin_page_hook( $plugin_page, 'tools.php' ) ) {
 			// There could be plugin specific params on the URL, so we need the whole query string.
 			if ( ! empty( $_SERVER['QUERY_STRING'] ) ) {
 				$query_string = $_SERVER['QUERY_STRING'];

wp-includes/version.php

@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.4-alpha-47219';
+$wp_version = '5.4-alpha-47220';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.