Move Walker_Page and Walker_PageDropdown into their own files via svn cp. Remove them from post-template.php. Load them in post.php.

`post-template.php` loads after `post.php` in `wp-settings.php`. It could probably also be loaded in `post.php`, but avoiding that for the moment.

See #33413.

Built from https://develop.svn.wordpress.org/trunk@34109


git-svn-id: http://core.svn.wordpress.org/trunk@34077 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post.php

@@ -7,5 +7,14 @@
  * @since 1.5.0
  */
 
+/** Core posts functionality */
 require_once( ABSPATH . WPINC . '/post-functions.php' );
+
+/** Walker_Page class */
+require_once( ABSPATH . WPINC . '/class-walker-page.php' );
+
+/** Walker_PageDropdown class */
+require_once( ABSPATH . WPINC . '/class-walker-page-dropdown.php' );
+
+/** WP_Post class */
 require_once( ABSPATH . WPINC . '/class-wp-post.php' );