Posts, Post types: Prevent get_page_by_title() parsing query twice.

In `get_page_by_title()` access the populated `WP_Query::posts` property directly rather than via the `WP_Query::get_posts()` method. This removes unnecessary reprocessing of the query.

Follow up to [54234].

Props david.binda, mukesh27, spacedmonkey.
Fixes #56721.


Built from https://develop.svn.wordpress.org/trunk@54377


git-svn-id: http://core.svn.wordpress.org/trunk@53936 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post.php

@@ -5787,7 +5787,7 @@ function get_page_by_title( $page_title, $output = OBJECT, $post_type = 'page' )
 		'order'                  => 'ASC',
 	);
 	$query = new WP_Query( $args );
-	$pages = $query->get_posts();
+	$pages = $query->posts;
 
 	if ( empty( $pages ) ) {
 		return null;