fix: makes keyed each blocks consistent between dev and prod (#10500)

.changeset/spotty-rocks-destroy.md

@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: makes keyed each blocks consistent between dev and prod

packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js

@@ -2383,8 +2383,7 @@ export const template_visitors = {
 					/** @type {import('estree').BlockStatement} */ (context.visit(node.fallback))
 				)
 			: b.literal(null);
-		const key_function =
+		const key_function = node.key
-			node.key && ((each_type & EACH_ITEM_REACTIVE) !== 0 || context.state.options.dev)
 			? b.arrow(
 					[node.context.type === 'Identifier' ? node.context : b.id('$$item'), index],
 					b.block(