Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 21377)
+++ wp-includes/user.php	(working copy)
@@ -1243,14 +1243,19 @@
  * @uses do_action() Calls 'profile_update' hook when updating giving the user's ID
  * @uses do_action() Calls 'user_register' hook when creating a new user giving the user's ID
  *
- * @param array $userdata An array of user data.
+ * @param mixed $userdata An array of user data or a user object of type stdClass or WP_User.
  * @return int|WP_Error The newly created user's ID or a WP_Error object if the user could not be created.
  */
-function wp_insert_user($userdata) {
+function wp_insert_user( $userdata ) {
 	global $wpdb;
 
-	extract($userdata, EXTR_SKIP);
+	if ( is_a( $userdata, 'stdClass' ) )
+		$userdata = get_object_vars( $userdata );
+	elseif ( is_a( $userdata, 'WP_User' ) )
+		$userdata = $userdata->to_array();
 
+	extract( $userdata, EXTR_SKIP );
+
 	// Are we updating or creating?
 	if ( !empty($ID) ) {
 		$ID = (int) $ID;
@@ -1390,16 +1395,21 @@
  * @see wp_insert_user() For what fields can be set in $userdata
  * @uses wp_insert_user() Used to update existing user or add new one if user doesn't exist already
  *
- * @param array $userdata An array of user data.
+ * @param mixed $userdata An array of user data or a user object of type stdClass or WP_User.
  * @return int The updated user's ID.
  */
 function wp_update_user($userdata) {
+	if ( is_a( $userdata, 'stdClass' ) )
+		$userdata = get_object_vars( $userdata );
+	elseif ( is_a( $userdata, 'WP_User' ) )
+		$userdata = $userdata->to_array();
+
 	$ID = (int) $userdata['ID'];
 
 	// First, get all of the original fields
 	$user_obj = get_userdata( $ID );
 
-	$user = get_object_vars( $user_obj->data );
+	$user = $user_obj->to_array();
 
 	// Add additional custom fields
 	foreach ( _get_additional_user_keys( $user_obj ) as $key ) {
Index: wp-includes/capabilities.php
===================================================================
--- wp-includes/capabilities.php	(revision 21377)
+++ wp-includes/capabilities.php	(working copy)
@@ -636,6 +636,17 @@
 		return $this->__isset( $key );
 	}
 
+	/*
+	 * Return an array representation.
+	 *
+	 * @since 3.5.0
+	 *
+	 * @return array Array representation.
+	 */
+	function to_array() {
+		return get_object_vars( $this->data );
+	}
+
 	/**
 	 * Set up capability object properties.
 	 *
Index: wp-admin/includes/user.php
===================================================================
--- wp-admin/includes/user.php	(revision 21377)
+++ wp-admin/includes/user.php	(working copy)
@@ -156,9 +156,9 @@
 		return $errors;
 
 	if ( $update ) {
-		$user_id = wp_update_user( get_object_vars( $user ) );
+		$user_id = wp_update_user( $user );
 	} else {
-		$user_id = wp_insert_user( get_object_vars( $user ) );
+		$user_id = wp_insert_user( $user );
 		wp_new_user_notification( $user_id, isset($_POST['send_password']) ? $pass1 : '' );
 	}
 	return $user_id;
Index: wp-admin/user-edit.php
===================================================================
--- wp-admin/user-edit.php	(revision 21377)
+++ wp-admin/user-edit.php	(working copy)
@@ -82,11 +82,12 @@
 if ( is_multisite() && IS_PROFILE_PAGE && isset( $_GET[ 'newuseremail' ] ) && $current_user->ID ) {
 	$new_email = get_option( $current_user->ID . '_new_email' );
 	if ( $new_email[ 'hash' ] == $_GET[ 'newuseremail' ] ) {
+		$user = new stdClass;
 		$user->ID = $current_user->ID;
 		$user->user_email = esc_html( trim( $new_email[ 'newemail' ] ) );
 		if ( $wpdb->get_var( $wpdb->prepare( "SELECT user_login FROM {$wpdb->signups} WHERE user_login = %s", $current_user->user_login ) ) )
 			$wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->signups} SET user_email = %s WHERE user_login = %s", $user->user_email, $current_user->user_login ) );
-		wp_update_user( get_object_vars( $user ) );
+		wp_update_user( $user );
 		delete_option( $current_user->ID . '_new_email' );
 		wp_redirect( add_query_arg( array('updated' => 'true'), self_admin_url( 'profile.php' ) ) );
 		die();