Add tests to deal with variable declarations in for loop initialization

test/runtime/samples/var-store-in-for-init-destructured/_config.js

@@ -0,0 +1,3 @@
+export default {
+  html: '<p>33</p><p>32</p>'
+};

test/runtime/samples/var-store-in-for-init-destructured/main.svelte

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+<script>
+  import { writable } from "svelte/store";
+  for (var { a = writable(4), z: b } = { z: writable(3) }; $a * $b < 1000; ) {
+    a.update(c => c + 1);
+    b.update(b => b + 1);
+  }
+</script>
+
+<p>{$a}</p>
+<p>{$b}</p>

test/runtime/samples/var-store-in-for-init/_config.js

@@ -0,0 +1,3 @@
+export default {
+  html: '<p>0</p><p>1</p><p>2</p><p>3</p><p>4</p>'
+};

test/runtime/samples/var-store-in-for-init/main.svelte

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+<script>
+  import { writable } from "svelte/store";
+  const array = [];
+  for (var i = writable(0); $i < 5; ) {
+    array.push($i);
+    i.update(n => n + 1);
+  }
+</script>
+
+{#each array as a}
+  <p>{a}</p>
+{/each}