Feeds: Adjust the `do_feed_{$feed}` hook name to actually be dynamic, rather than pre-storing the tag name in a variable and referencing that.

Props johnbillion.
Fixes #34264.

Built from https://develop.svn.wordpress.org/trunk@35097


git-svn-id: http://core.svn.wordpress.org/trunk@35062 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/functions.php

@@ -1165,13 +1165,14 @@ function do_feed() {
 	/**
 	 * Fires once the given feed is loaded.
 	 *
-	 * The dynamic hook name, $hook, refers to the feed name.
+	 * The dynamic portion of the hook name, `$feed`, refers to the feed template name.
+	 * Possible values include: 'rdf', 'rss', 'rss2', and 'atom'.
 	 *
 	 * @since 2.1.0
 	 *
 	 * @param bool $is_comment_feed Whether the feed is a comment feed.
 	 */
-	do_action( $hook, $wp_query->is_comment_feed );
+	do_action( "do_feed_{$feed}", $wp_query->is_comment_feed );
 }
 
 /**

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-35096';
+$wp_version = '4.4-alpha-35097';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.