Customize: Prevent JS error in Links widget when selective refresh is enabled

This prevents erroneously replacing the `data-customize-partial-id` when only the `id` attribute should be replaced. 

Props dlh, costdev, nikeo, greenshady.
Fixes #39451.


git-svn-id: https://develop.svn.wordpress.org/trunk@54125 602fd350-edb4-49c9-b593-d223f7449a82

Author: westonruter

src/wp-includes/widgets/class-wp-widget-links.php

@@ -48,7 +48,7 @@ public function widget( $args, $instance ) {
 		$order            = 'rating' === $orderby ? 'DESC' : 'ASC';
 		$limit            = isset( $instance['limit'] ) ? $instance['limit'] : -1;
 
-		$before_widget = preg_replace( '/id="[^"]*"/', 'id="%id"', $args['before_widget'] );
+		$before_widget = preg_replace( '/ id="[^"]*"/', ' id="%id"', $args['before_widget'] );
 
 		$widget_links_args = array(
 			'title_before'     => $args['before_title'],