Unable to store back an object retrieved from IndexedDB

[tomyeh]

If the data is a list and it contains a map, we can't store back the data if it was retrieved previously.

Test Code:

main() async {
  final db = await window.indexedDB.open("test", version: 1,
      onUpgradeNeeded: (e) {
        final Database db = e.target.result;
        if (!db.objectStoreNames.contains("test"))
          db.createObjectStore("test", keyPath: "id");
      });

  final os = db.transaction("test", "readwrite")
  .objectStore("test");

  await os.put({"id": "foo", "data": [{"f": 123}]}); //OK
  final val = await os.getObject("foo");
  await os.put(val); //FAILED
  print("DONE");
}

It threw an exception:

DataCloneError: Failed to execute 'put' on 'IDBObjectStore': An object could not be cloned.
#0      Blink_JsNative_DomException.callMethod (dart:_blink:38965)
#1      BlinkIDBObjectStore.put_Callback_1_ (dart:_blink:14724)
#2      ObjectStore._put (dart:indexed_db:1127)
#3      ObjectStore.put (dart:indexed_db:924)
...

Dart SDK: 1.24.2