Templates: Move old theme attr injection function to deprecated.php.

Move the now-deprecated function `_inject_theme_attribute_in_block_template_content` from `wp-includes/block-template-utils.php` to `wp-includes/deprecated.php`.

Follow-up [56719].
Props spacedmonkey, davidbaumwald, mukesh27.
See #59452.

git-svn-id: https://develop.svn.wordpress.org/trunk@56722 602fd350-edb4-49c9-b593-d223f7449a82

Author: ockham

src/wp-includes/block-template-utils.php

@@ -470,50 +470,6 @@ function _flatten_blocks( &$blocks ) {
 	return $all_blocks;
 }
 
-/**
- * Parses wp_template content and injects the active theme's
- * stylesheet as a theme attribute into each wp_template_part
- *
- * @since 5.9.0
- * @deprecated 6.4.0 Use traverse_and_serialize_blocks( parse_blocks( $template_content ), '_inject_theme_attribute_in_template_part_block' ) instead.
- * @access private
- *
- * @param string $template_content serialized wp_template content.
- * @return string Updated 'wp_template' content.
- */
-function _inject_theme_attribute_in_block_template_content( $template_content ) {
-	_deprecated_function(
-		__FUNCTION__,
-		'6.4.0',
-		'traverse_and_serialize_blocks( parse_blocks( $template_content ), "_inject_theme_attribute_in_template_part_block" )'
-	);
-
-	$has_updated_content = false;
-	$new_content         = '';
-	$template_blocks     = parse_blocks( $template_content );
-
-	$blocks = _flatten_blocks( $template_blocks );
-	foreach ( $blocks as &$block ) {
-		if (
-			'core/template-part' === $block['blockName'] &&
-			! isset( $block['attrs']['theme'] )
-		) {
-			$block['attrs']['theme'] = get_stylesheet();
-			$has_updated_content     = true;
-		}
-	}
-
-	if ( $has_updated_content ) {
-		foreach ( $template_blocks as &$block ) {
-			$new_content .= serialize_block( $block );
-		}
-
-		return $new_content;
-	}
-
-	return $template_content;
-}
-
 /**
  * Injects the active theme's stylesheet as a `theme` attribute
  * into a given template part block.

src/wp-includes/deprecated.php

@@ -6040,3 +6040,47 @@ function wp_img_tag_add_decoding_attr( $image, $context ) {
 
 	return $image;
 }
+
+/**
+ * Parses wp_template content and injects the active theme's
+ * stylesheet as a theme attribute into each wp_template_part
+ *
+ * @since 5.9.0
+ * @deprecated 6.4.0 Use traverse_and_serialize_blocks( parse_blocks( $template_content ), '_inject_theme_attribute_in_template_part_block' ) instead.
+ * @access private
+ *
+ * @param string $template_content serialized wp_template content.
+ * @return string Updated 'wp_template' content.
+ */
+function _inject_theme_attribute_in_block_template_content( $template_content ) {
+	_deprecated_function(
+		__FUNCTION__,
+		'6.4.0',
+		'traverse_and_serialize_blocks( parse_blocks( $template_content ), "_inject_theme_attribute_in_template_part_block" )'
+	);
+
+	$has_updated_content = false;
+	$new_content         = '';
+	$template_blocks     = parse_blocks( $template_content );
+
+	$blocks = _flatten_blocks( $template_blocks );
+	foreach ( $blocks as &$block ) {
+		if (
+			'core/template-part' === $block['blockName'] &&
+			! isset( $block['attrs']['theme'] )
+		) {
+			$block['attrs']['theme'] = get_stylesheet();
+			$has_updated_content     = true;
+		}
+	}
+
+	if ( $has_updated_content ) {
+		foreach ( $template_blocks as &$block ) {
+			$new_content .= serialize_block( $block );
+		}
+
+		return $new_content;
+	}
+
+	return $template_content;
+}