--- a/js/src/vm/Iteration.cpp
+++ b/js/src/vm/Iteration.cpp
@@ -832,21 +832,21 @@ IteratorHashPolicy::match(PropertyIterat
     return ArrayEqual(reinterpret_cast<ReceiverGuard*>(ni->guardsBegin()), lookup.guards,
                       ni->guardCount());
 }
 
 static inline bool
 CanCompareIterableObjectToCache(JSObject* obj)
 {
     if (obj->isNative()) {
-        return obj->as<NativeObject>().hasEmptyElements();
+        return obj->as<NativeObject>().getDenseInitializedLength() == 0;
     }
     if (obj->is<UnboxedPlainObject>()) {
         if (UnboxedExpandoObject* expando = obj->as<UnboxedPlainObject>().maybeExpando()) {
-            return expando->hasEmptyElements();
+            return expando->getDenseInitializedLength() == 0;
         }
         return true;
     }
     return false;
 }
 
 using ReceiverGuardVector = Vector<ReceiverGuard, 8>;
 
@@ -894,17 +894,17 @@ LookupInIteratorCache(JSContext* cx, JSO
     return iterobj;
 }
 
 static bool
 CanStoreInIteratorCache(JSObject* obj)
 {
     do {
         if (obj->isNative()) {
-            MOZ_ASSERT(obj->as<NativeObject>().hasEmptyElements());
+            MOZ_ASSERT(obj->as<NativeObject>().getDenseInitializedLength() == 0);
 
             // Typed arrays have indexed properties not captured by the Shape guard.
             // Enumerate hooks may add extra properties.
             const Class* clasp = obj->getClass();
             if (MOZ_UNLIKELY(IsTypedArrayClass(clasp))) {
                 return false;
             }
             if (MOZ_UNLIKELY(clasp->getNewEnumerate() || clasp->getEnumerate())) {