Editor: Ensure block style name does not contain spaces before creating the class.

This change adds a check to ensure there is no spaces in block style variation names before generating the class. Returns `false` and a `_doing_it_wrong()` message if a space is detected.

Props amustaque97, costdev, hellofromtonya, pbiron, SergeyBiryukov, afragen.
Fixes #54296.


git-svn-id: https://develop.svn.wordpress.org/trunk@52261 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-block-styles-registry.php

@@ -62,6 +62,15 @@ final class WP_Block_Styles_Registry {
 			return false;
 		}
 
+		if ( str_contains( $style_properties['name'], ' ' ) ) {
+			_doing_it_wrong(
+				__METHOD__,
+				__( 'Block style name must not contain any spaces.' ),
+				'5.9.0'
+			);
+			return false;
+		}
+
 		$block_style_name = $style_properties['name'];
 
 		if ( ! isset( $this->registered_block_styles[ $block_name ] ) ) {