REST API: Remove rest_get_post filter and get_post abstraction.

This filter was originally introduced in https://github.com/WP-API/WP-API/pull/2535 to support Customizer Changesets (née Transactions). This is a super broad filter and doesn't really fit with the design of the API, nor is it (arguably) the right level to do this.

Props rmccue.
Fixes #38701.


git-svn-id: https://develop.svn.wordpress.org/trunk@39161 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/rest-api/endpoints/class-wp-rest-controller.php

@@ -580,41 +580,6 @@ abstract class WP_REST_Controller {
 		return $endpoint_args;
 	}
 
-	/**
-	 * Retrieves post data given a post ID or post object.
-	 *
-	 * This is a subset of the functionality of the `get_post()` function, with
-	 * the additional functionality of having `the_post` action done on the
-	 * resultant post object. This is done so that plugins may manipulate the
-	 * post that is used in the REST API.
-	 *
-	 * @since 4.7.0
-	 * @access public
-	 *
-	 * @see get_post()
-	 * @global WP_Query $wp_query
-	 *
-	 * @param int|WP_Post $post Post ID or object. Defaults to global `$post` object.
-	 * @return WP_Post|null A WP_Post object when successful, otherwise null.
-	 */
-	public function get_post( $post ) {
-		$post_obj = get_post( $post );
-
-		/**
-		 * Filters the post in the context of a REST request.
-		 *
-		 * Allows plugins to filter the post object as returned by WP_REST_Controller::get_post().
-		 *
-		 * @since 4.7.0
-		 *
-		 * @param WP_Post|null $post_obj The post object as returned by get_post().
-		 * @param int|WP_Post  $post     The original value used to obtain the post object.
-		 */
-		$post = apply_filters( 'rest_the_post', $post_obj, $post );
-
-		return $post;
-	}
-
 	/**
 	 * Sanitizes the slug value.
 	 *