Posts, Post Types: Set post filter in update_post_cache().

Ensure the post cache is primed with raw sanitized data. This resolves an inconsistency between how posts retrieved via `get_post()` vs `WP_Query` are cached.

This prevents `sanitize_post( $post, 'raw' )` being run multiple times on a cached post. This can happen over 20 times per post on some page loads so avoiding this will provide a noticeable performance boost.

Props Cybr, SergeyBiryukov, peterwilsoncc, hellofromTonya, costdev.
Fixes #50567.


Built from https://develop.svn.wordpress.org/trunk@53042


git-svn-id: http://core.svn.wordpress.org/trunk@52631 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post.php

@@ -7374,6 +7374,9 @@ function update_post_cache( &$posts ) {
 
 	$data = array();
 	foreach ( $posts as $post ) {
+		if ( empty( $post->filter ) || 'raw' !== $post->filter ) {
+			$post = sanitize_post( $post, 'raw' );
+		}
 		$data[ $post->ID ] = $post;
 	}
 	wp_cache_add_multiple( $data, 'posts' );