Fix/reference leak

lib/quickjs/ffi.dart

@@ -255,9 +255,8 @@ void jsFreeRuntime(
   final referenceleak = <String>[];
   final opaque = runtimeOpaques[rt];
   if (opaque != null) {
-    while (true) {
-      final ref = opaque._ref.firstWhereOrNull((ref) => ref is JSRefLeakable);
-      if (ref == null) break;
+    while (opaque._ref.isNotEmpty) {
+      final ref = opaque._ref.first;
       ref.destroy();
       runtimeOpaques[rt]?._ref.remove(ref);
     }

test/flutter_js_test.dart

@@ -1,3 +1,5 @@
+import 'package:flutter_js/extensions/fetch.dart';
+import 'package:flutter_js/extensions/xhr.dart';
 import 'package:flutter_js/flutter_js.dart';
 import 'package:flutter_test/flutter_test.dart';
 
@@ -7,7 +9,7 @@ void main() {
   late JavascriptRuntime jsRuntime;
 
   setUp(() {
-    jsRuntime = getJavascriptRuntime();
+    jsRuntime = getJavascriptRuntime(xhr: true);
   });
 
   tearDown(() {
@@ -24,4 +26,38 @@ void main() {
     expect(result.rawResult, equals(125));
     expect(result.stringResult, equals('125'));
   });
+
+  test('leak test', () async {
+    final jsRt = getJavascriptRuntime();
+    jsRt.evaluate('''
+    delay = (delayInms) => {
+      return new Promise((resolve) => setTimeout(resolve, delayInms));
+    }
+    ''');
+    jsRt.evaluate('''
+    async function asyncTest(del = 30) {
+      try {
+        console.log(`Starting \$\{del\}...`);
+        while (del > 0) {
+          console.log(del);
+          await delay(1000);
+          del--;
+        }
+        console.log(`Done \$\{del\}`);
+        return `Done \$\{del\}`;
+      } catch (e) {
+        console.log(`Error in asyncTest: \$\{e\}`);
+        return "Error";
+      }
+    }
+    ''');
+    await jsRt.enableFetch();
+    jsRt.enableHandlePromises();
+    jsRt.enableXhr();
+    final promise = await jsRt.evaluateAsync('asyncTest(2)');
+    jsRt.executePendingJob();
+    JsEvalResult asyncResult = await jsRt.handlePromise(promise);
+    print('${asyncResult.stringResult}, ${asyncResult.stringResult}');
+    jsRt.dispose();
+  });
 }