diff --git a/src/wp-includes/customize/class-wp-widget-area-customize-control.php b/src/wp-includes/customize/class-wp-widget-area-customize-control.php
index 7b0a791125..6a93766595 100644
--- a/src/wp-includes/customize/class-wp-widget-area-customize-control.php
+++ b/src/wp-includes/customize/class-wp-widget-area-customize-control.php
@@ -15,9 +15,31 @@
  * @see WP_Customize_Control
  */
 class WP_Widget_Area_Customize_Control extends WP_Customize_Control {
+
+	/**
+	 * Customize control type.
+	 *
+	 * @since 3.9.0
+	 * @access public
+	 * @var string
+	 */
 	public $type = 'sidebar_widgets';
+
+	/**
+	 * Sidebar ID.
+	 *
+	 * @since 3.9.0
+	 * @access public
+	 * @var int|string
+	 */
 	public $sidebar_id;
 
+	/**
+	 * Refreshes the parameters passed to the JavaScript via JSON.
+	 *
+	 * @since 3.9.0
+	 * @access public
+	 */
 	public function to_json() {
 		parent::to_json();
 		$exported_properties = array( 'sidebar_id' );
@@ -27,6 +49,9 @@ class WP_Widget_Area_Customize_Control extends WP_Customize_Control {
 	}
 
 	/**
+	 * Renders the control's content.
+	 *
+	 * @since 3.9.0
 	 * @access public
 	 */
 	public function render_content() {