From 3f5d5a5aabbbdd1687afe828a039828b5f5b880e Mon Sep 17 00:00:00 2001
From: Andrew Serong <14988353+andrewserong@users.noreply.github.com>
Date: Thu, 28 Jul 2022 15:32:32 +1000
Subject: [PATCH] Theme JSON Resolver: Update cache check to also check that
 the object is an instance of the Gutenberg version (#42756)

* Theme JSON Resolver: Update cache check to also check that the object is an instance of the Gutenberg version

* Add comment for when the resolver is backported to core
---
 lib/experimental/class-wp-theme-json-resolver-gutenberg.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/experimental/class-wp-theme-json-resolver-gutenberg.php b/lib/experimental/class-wp-theme-json-resolver-gutenberg.php
index adf5803de561aa..a4d4e4dfc7066d 100644
--- a/lib/experimental/class-wp-theme-json-resolver-gutenberg.php
+++ b/lib/experimental/class-wp-theme-json-resolver-gutenberg.php
@@ -33,7 +33,8 @@ public static function get_theme_data( $deprecated = array(), $settings = array(
 			_deprecated_argument( __METHOD__, '5.9' );
 		}
 
-		if ( null === static::$theme ) {
+		// When backporting to core, remove the instanceof Gutenberg class check, as it is only required for the Gutenberg plugin.
+		if ( null === static::$theme || ! static::$theme instanceof WP_Theme_JSON_Gutenberg ) {
 			$theme_json_data = static::read_json_file( static::get_file_path_from_theme( 'theme.json' ) );
 			$theme_json_data = static::translate( $theme_json_data, wp_get_theme()->get( 'TextDomain' ) );
 			$theme_json_data = gutenberg_add_registered_webfonts_to_theme_json( $theme_json_data );