Feeds: Simplify logic for checking if the `do_feed_{$feed}` action is hooked to any callbacks.

See [35097] for where the aforementioned hook was renamed to actually be dynamic, thus rendering creation of the extra `$hook` variable moot.

See #34264.

Built from https://develop.svn.wordpress.org/trunk@35098


git-svn-id: http://core.svn.wordpress.org/trunk@35063 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -1158,9 +1158,9 @@ function do_feed() {
 	if ( $feed == '' || $feed == 'feed' )
 		$feed = get_default_feed();
 
-	$hook = 'do_feed_' . $feed;
-	if ( ! has_action( $hook ) )
+	if ( ! has_action( "do_feed_{$feed}" ) ) {
 		wp_die( __( 'ERROR: This is not a valid feed template.' ), '', array( 'response' => 404 ) );
+	}
 
 	/**
 	 * Fires once the given feed is loaded.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-35097';
+$wp_version = '4.4-alpha-35098';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.