test: use setImmediate() in test-heapdump-shadowrealm.js

With a tight loop the GC may not have enough time to kick in.
Try setImmediate() instead.

test/pummel/test-heapdump-shadow-realm.js

@@ -4,29 +4,39 @@ require('../common');
 const { validateSnapshotNodes } = require('../common/heap');
 
 validateSnapshotNodes('Node / ShadowRealm', []);
-const realm = new ShadowRealm();
-{
-  // Create a bunch of un-referenced ShadowRealms to make sure the heap
-  // snapshot can handle it.
-  for (let i = 0; i < 100; i++) {
-    const realm = new ShadowRealm();
+
+let realm;
+let counter = 0;
+// Create a bunch of un-referenced ShadowRealms to make sure the heap
+// snapshot can handle it.
+function createRealms() {
+  // Use setImmediate to give GC some time to kick in to avoid OOM.
+  if (counter++ < 100) {
+    realm = new ShadowRealm();
+    realm.evaluate('undefined');
+    setImmediate(createRealms);
+  } else {
+    validateHeap();
+    // Keep the realm alive.
     realm.evaluate('undefined');
   }
 }
-validateSnapshotNodes('Node / Environment', [
-  {
-    children: [
-      { node_name: 'Node / shadow_realms', edge_name: 'shadow_realms' },
-    ],
-  },
-]);
-validateSnapshotNodes('Node / shadow_realms', [
-  {
-    children: [
-      { node_name: 'Node / ShadowRealm' },
-    ],
-  },
-]);
 
-// Keep the realm alive.
-realm.evaluate('undefined');
+function validateHeap() {
+  validateSnapshotNodes('Node / Environment', [
+    {
+      children: [
+        { node_name: 'Node / shadow_realms', edge_name: 'shadow_realms' },
+      ],
+    },
+  ]);
+  validateSnapshotNodes('Node / shadow_realms', [
+    {
+      children: [
+        { node_name: 'Node / ShadowRealm' },
+      ],
+    },
+  ]);
+}
+
+createRealms();