Don't return empty themes in `wp_prepare_themes_for_js()`.

see #32002.
Built from https://develop.svn.wordpress.org/trunk@32264


git-svn-id: http://core.svn.wordpress.org/trunk@32235 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/theme.php

@@ -502,7 +502,8 @@ function wp_prepare_themes_for_js( $themes = null ) {
 	 * @param array $prepared_themes Array of themes.
 	 */
 	$prepared_themes = apply_filters( 'wp_prepare_themes_for_js', $prepared_themes );
-	return array_values( $prepared_themes );
+	$prepared_themes = array_values( $prepared_themes );
+	return array_filter( $prepared_themes );
 }
 
 /**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.2-RC3-32261';
+$wp_version = '4.2-RC3-32264';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.