Bootstrap: Use `dirname()` when loading `class-wp-hook.php` from `plugin.php`.

To allow `plugin.php` to be loaded before the rest of WordPress is loaded, it cannot rely on WordPress constants, such as `ABSPATH` and `WPINC`.

Instead, we can assume that `class-wp-hook.php` will be in the same directory as `plugin.php`, so `dirname( __FILE__ )` will give us the correct path to load from.

Props pento, dd32.
Fixes #37707.


Built from https://develop.svn.wordpress.org/trunk@38589


git-svn-id: http://core.svn.wordpress.org/trunk@38532 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/plugin.php

@@ -22,7 +22,7 @@
  */
 
 // Initialize the filter globals.
-require( ABSPATH . WPINC . '/class-wp-hook.php' );
+require( dirname( __FILE__ ) . '/class-wp-hook.php' );
 
 /** @var WP_Hook[] $wp_filter */
 global $wp_filter, $wp_actions, $wp_current_filter;

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-alpha-38588';
+$wp_version = '4.7-alpha-38589';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.