Editor: add iframe around post editor.

Adds an iframe around the post editor only if all registered blocks are v3 or higher.

Props ellatrix, mukesh27, costdev, oandregal, ramonopoly.
Fixes #58626.


git-svn-id: https://develop.svn.wordpress.org/trunk@56047 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/script-loader.php

@@ -1629,7 +1629,7 @@ function wp_default_styles( $styles ) {
 	$styles->add(
 		'wp-block-editor-content',
 		"/wp-includes/css/dist/block-editor/content$suffix.css",
-		array()
+		array( 'wp-components' )
 	);
 
 	$wp_edit_blocks_dependencies = array(