For doc block types, favor bool over the few remaining booleans

See #32444.


git-svn-id: https://develop.svn.wordpress.org/trunk@32964 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-customize-manager.php

@@ -38,7 +38,7 @@ final class WP_Customize_Manager {
 	/**
 	 * Whether this is a Customizer pageload.
 	 *
-	 * @var boolean
+	 * @var bool
 	 */
 	protected $previewing = false;