Enqueue the registered assets (#50185)

* Enqueue again the registered assets

* Document and protect against 6.1 and 6.2

* Make sure the action runs earlier, as if it was from core

* Make linter happy

* Fix linting issues

---------

Co-authored-by: Andrew Serong <14988353+andrewserong@users.noreply.github.com>

Author: 2 people

lib/compat/wordpress-6.2/default-filters.php

@@ -23,3 +23,18 @@
  */
 add_action( 'start_previewing_theme', '_gutenberg_clean_theme_json_caches' );
 add_action( 'switch_theme', '_gutenberg_clean_theme_json_caches' );
+
+/**
+ * This is a temporary fix to ensure that the block editor styles are enqueued
+ * in the order the iframe expects.
+ *
+ * The wp_enqueue_registered_block_scripts_and_styles callback has been removed in core
+ * as of https://github.com/WordPress/wordpress-develop/pull/4356.
+ *
+ * However, Gutenberg supports WordPress 6.1 and 6.2, which still have this callback.
+ * Hence, why we remove it first and then re-add it.
+ *
+ * This way we make sure it still works the same in WordPress trunk, 6.1 and 6.2.
+ */
+remove_action( 'enqueue_block_editor_assets', 'wp_enqueue_registered_block_scripts_and_styles' );
+add_action( 'enqueue_block_editor_assets', 'wp_enqueue_registered_block_scripts_and_styles', 1 );