Plugin: Deprecate gutenberg_kses_allowedtags (#13460)

docs/designers-developers/developers/backward-compatibility/deprecations.md

@@ -23,6 +23,7 @@ The Gutenberg project's deprecation policy is intended to support backward compa
 - The PHP function `gutenberg_filter_post_type_labels` has been removed.
 - The PHP function `gutenberg_remove_wpcom_markdown_support` has been removed.
 - The PHP function `gutenberg_bulk_post_updated_messages` has been removed.
+- The PHP function `gutenberg_kses_allowedtags` has been removed.
 
 ## 4.5.0
 - `Dropdown.refresh()` has been deprecated as the contained `Popover` is now automatically refreshed.

gutenberg.php

@@ -527,19 +527,17 @@ function gutenberg_add_admin_body_class( $classes ) {
  * Adds attributes to kses allowed tags that aren't in the default list
  * and that Gutenberg needs to save blocks such as the Gallery block.
  *
+ * @deprecated 5.0.0
+ *
  * @param array $tags Allowed HTML.
  * @return array (Maybe) modified allowed HTML.
  */
 function gutenberg_kses_allowedtags( $tags ) {
-	if ( isset( $tags['img'] ) ) {
-		$tags['img']['data-link'] = true;
-		$tags['img']['data-id']   = true;
-	}
+	_deprecated_function( __FUNCTION__, '5.0.0' );
+
 	return $tags;
 }
 
-add_filter( 'wp_kses_allowed_html', 'gutenberg_kses_allowedtags', 10, 2 );
-
 /**
  * Adds the wp-embed-responsive class to the body tag if the theme has opted in to
  * Gutenberg responsive embeds.