skip array literal length optimization in presence of spread (#2325)

src/compile/render-dom/wrappers/EachBlock.ts

@@ -92,7 +92,9 @@ export default class EachBlockWrapper extends Wrapper {
 
 		this.index_name = this.node.index || renderer.component.get_unique_name(`${this.node.context}_index`);
 
-		const fixed_length = node.expression.node.type === 'ArrayExpression'
+		const fixed_length =
+			node.expression.node.type === 'ArrayExpression' &&
+			node.expression.node.elements.every(element => element.type !== 'SpreadElement')
 				? node.expression.node.elements.length
 				: null;