Move hash code from hidden string to a private symbol

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 959e8a003bfc6034aaeee42e9af02803ead366b8..52f373a8c0a15c2508ebc02bac222c8285e799e1 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -2540,7 +2540,8 @@ void NativeWeakMap::Set(Handle<Value> v8_key, Handle<Value> v8_value) {
     DCHECK(false);
     return;
   }
-  i::Runtime::WeakCollectionSet(weak_collection, key, value);
+  int32_t hash = i::Object::GetOrCreateHash(isolate, key)->value();
+  i::Runtime::WeakCollectionSet(weak_collection, key, value, hash);
 }