Editor: Use block settings to pass assets for the iframed editor

Backports changes applied in Gutenberg in https://github.com/WordPress/gutenberg/pull/37193.

Props zieladam.
See #55505.
Follow-up for [53157].



git-svn-id: https://develop.svn.wordpress.org/trunk@53160 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/deprecated.php

@@ -4301,3 +4301,13 @@ function wp_skip_spacing_serialization( $block_type ) {
 		array_key_exists( '__experimentalSkipSerialization', $spacing_support ) &&
 		$spacing_support['__experimentalSkipSerialization'];
 }
+
+/**
+ * Inject the block editor assets that need to be loaded into the editor's iframe as an inline script.
+ *
+ * @since 5.8.0
+ * @deprecated 6.0.0
+ */
+function wp_add_iframed_editor_assets_html() {
+	_deprecated_function( __FUNCTION__, '6.0.0' );
+}