Customize: Ensure that only sidebar sections are considered when comparing against sidebars.

In the Customizer a notice will show up if there is at least one registered sidebar with its section not being active. In order to achieve that, the count of registered sidebars is compared to the count of active sections in the Widgets panel. Prior to this change, the latter would incorrectly include any sections, even additional sections that do not correspond to a sidebar.

Fixes #43556.


git-svn-id: https://develop.svn.wordpress.org/trunk@43588 602fd350-edb4-49c9-b593-d223f7449a82

src/js/_enqueues/wp/customize/widgets.js

@@ -1634,7 +1634,7 @@
 				 */
 				getActiveSectionCount = function() {
 					return _.filter( panel.sections(), function( section ) {
-						return section.active();
+						return 'sidebar' === section.params.type && section.active();
 					} ).length;
 				};