Global Styles Revisions: Preserve block style variations in global styles revisions

When retrieving global styles revisions through the REST API, any block style variations (e.g., `styles.blocks.core/group.variations.my-variation`) are being removed during `WP_Theme_JSON` sanitization.

`WP_Theme_JSON` will only allow block style variations that are registered.

This means user modifications to any theme block style variations were being stripped from global styles revisions when retrieved via the REST API.

This commit registers theme-defined block style variations in `WP_REST_Global_Styles_Revisions_Controller::prepare_item_for_response` so that they can be properly parsed by `WP_Theme_JSON`, and therefore added to the global styles revisions REST API GET response.

Props ramonopoly, aaronrobertshaw, ellatrix.

Fixes #64292.



git-svn-id: https://develop.svn.wordpress.org/trunk@61301 602fd350-edb4-49c9-b593-d223f7449a82

Author: ramonjd

src/wp-includes/rest-api/endpoints/class-wp-rest-global-styles-revisions-controller.php

@@ -312,6 +312,15 @@ public function prepare_item_for_response( $post, $request ) {
 		$theme_json = null;
 
 		if ( ! empty( $global_styles_config['styles'] ) || ! empty( $global_styles_config['settings'] ) ) {
+			/*
+			 * Register block style variations from the theme data.
+			 * This is required so the variations pass sanitization of theme.json data.
+			 */
+			if ( ! empty( $global_styles_config['styles']['blocks'] ) ) {
+				$variations = WP_Theme_JSON_Resolver::get_style_variations( 'block' );
+				wp_register_block_style_variations_from_theme_json_partials( $variations );
+			}
+
 			$theme_json           = new WP_Theme_JSON( $global_styles_config, 'custom' );
 			$global_styles_config = $theme_json->get_raw_data();
 			if ( rest_is_field_included( 'settings', $fields ) ) {