Customize: Do not attempt to count uncountable value.

Props dlh.
Merges [43480] to the 4.9 branch.
Fixes #44104.
Built from https://develop.svn.wordpress.org/branches/4.9@43481


git-svn-id: http://core.svn.wordpress.org/branches/4.9@43308 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-nav-menus.php

@@ -313,7 +313,7 @@ final class WP_Customize_Nav_Menus {
 
 		// Prepend list of posts with nav_menus_created_posts search results on first page.
 		$nav_menus_created_posts_setting = $this->manager->get_setting( 'nav_menus_created_posts' );
-		if ( 1 === $args['pagenum'] && $nav_menus_created_posts_setting && count( $nav_menus_created_posts_setting ) > 0 ) {
+		if ( 1 === $args['pagenum'] && $nav_menus_created_posts_setting && count( $nav_menus_created_posts_setting->value() ) > 0 ) {
 			$stub_post_query = new WP_Query( array_merge(
 				$query,
 				array(

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9.8-alpha-43479';
+$wp_version = '4.9.8-alpha-43481';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.