add test

Author: ota-meshi

tests/fixtures/parser/ast/at-const02-input.svelte

@@ -0,0 +1,15 @@
+<script>
+export let boxes;
+</script>
+
+{#each boxes as box}
+{
+@const
+area
+=
+box.width
+*
+box.height
+}
+{box.width} * {box.height} = {area}
+{/each}