Fix the site editor Admin Bar menu item (WordPress#61851)

Co-authored-by: youknowriad <youknowriad@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: ellatrix <ellatrix@git.wordpress.org>

backport-changelog/6.6/6605.md

@@ -0,0 +1,3 @@
+https://github.com/WordPress/wordpress-develop/pull/6605
+
+* https://github.com/WordPress/gutenberg/pull/61851

lib/compat/wordpress-6.6/admin-bar.php

@@ -0,0 +1,48 @@
+<?php
+/**
+ * Changes to the WordPress admin bar.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Adds the "Site Editor" link to the Toolbar.
+ *
+ * @since 5.9.0
+ * @since 6.3.0 Added `$_wp_current_template_id` global for editing of current template directly from the admin bar.
+ * @since 6.6.0 Added the canvas argument to the url.
+ *
+ * @global string $_wp_current_template_id
+ *
+ * @param WP_Admin_Bar $wp_admin_bar The WP_Admin_Bar instance.
+ */
+function gutenberg_admin_bar_edit_site_menu( $wp_admin_bar ) {
+	global $_wp_current_template_id;
+
+	// Don't show if a block theme is not activated.
+	if ( ! wp_is_block_theme() ) {
+		return;
+	}
+
+	// Don't show for users who can't edit theme options or when in the admin.
+	if ( ! current_user_can( 'edit_theme_options' ) || is_admin() ) {
+		return;
+	}
+
+	$wp_admin_bar->add_node(
+		array(
+			'id'    => 'site-editor',
+			'title' => __( 'Site Editor' ),
+			'href'  => add_query_arg(
+				array(
+					'postType' => 'wp_template',
+					'postId'   => $_wp_current_template_id,
+					'canvas'   => 'edit',
+				),
+				admin_url( 'site-editor.php' )
+			),
+		)
+	);
+}
+remove_action( 'admin_bar_menu', 'wp_admin_bar_edit_site_menu', 40 );
+add_action( 'admin_bar_menu', 'gutenberg_admin_bar_edit_site_menu', 41 );

lib/load.php

@@ -130,6 +130,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/compat/wordpress-6.5/script-loader.php';
 
 // WordPress 6.6 compat.
+require __DIR__ . '/compat/wordpress-6.6/admin-bar.php';
 require __DIR__ . '/compat/wordpress-6.6/compat.php';
 require __DIR__ . '/compat/wordpress-6.6/resolve-patterns.php';
 require __DIR__ . '/compat/wordpress-6.6/block-bindings/pattern-overrides.php';