load dynamic code lazily

Author: trueadm

packages/svelte/src/internal/client/block.js

@@ -175,6 +175,8 @@ export function create_each_block(flags, anchor) {
  */
 export function create_each_item_block(item, index, key) {
 	return {
+		// animate transition
+		a: null,
 		// dom
 		d: null,
 		// effect