Index: src/wp-includes/class-walker-comment.php
===================================================================
--- src/wp-includes/class-walker-comment.php	(revision 41971)
+++ src/wp-includes/class-walker-comment.php	(working copy)
@@ -192,6 +192,26 @@
 	}
 
 	/**
+	 * After the element output has started.
+	 * 
+	 * @param string     $output  Used to append additional content after an element. Passed by reference.
+	 * @param WP_Comment $comment Comment data object.
+	 * @param int        $depth   Optional. Depth of the current comment in reference to parents. Default 0.
+	 * @param array      $args    Optional. An array of arguments. Default empty array.
+	 */
+	public function start_el_after( &$output, $comment, $depth = 0, $args = array() ) {
+		/**
+		 * Filter to add content after comment HTML.
+		 *
+		 * @param string     $after_comment HTML after a comment. Default empty string
+		 * @param WP_Comment $comment       The current comment object. Default current comment.
+		 * @param int        $depth         Depth of the current comment in reference to parents.
+		 * @param array      $args          An array of arguments.
+		 */
+		$output .= apply_filters( 'after_comment', '', $comment, $depth, $args );
+	}
+
+	/**
 	 * Ends the element output, if needed.
 	 *
 	 * @since 2.7.0
Index: src/wp-includes/class-wp-walker.php
===================================================================
--- src/wp-includes/class-wp-walker.php	(revision 41971)
+++ src/wp-includes/class-wp-walker.php	(working copy)
@@ -62,6 +62,21 @@
 	public function start_lvl( &$output, $depth = 0, $args = array() ) {}
 
 	/**
+	 * After the element output has started.
+	 *
+	 * The $args parameter holds additional values that may be used with the child class methods.
+	 *
+	 * @since X.X.X
+	 * @abstract
+	 *
+	 * @param string $output Passed by reference. Used to append additional content.
+	 * @param object $object The data object.
+	 * @param int    $depth  Depth of the item.
+	 * @param array  $args   An array of additional arguments.
+	 */
+	public function start_el_after( &$output, $object, $depth = 0, $args = array() ) {}
+
+	/**
 	 * Ends the list of after the elements are added.
 	 *
 	 * The $args parameter holds additional values that may be used with the child
@@ -143,6 +158,7 @@
 
 		$cb_args = array_merge( array(&$output, $element, $depth), $args);
 		call_user_func_array(array($this, 'start_el'), $cb_args);
+		call_user_func_array( array( $this, 'start_el_after' ), $cb_args );
 
 		// descend only when the depth is right and there are childrens for this element
 		if ( ($max_depth == 0 || $max_depth > $depth+1 ) && isset( $children_elements[$id]) ) {