[strong] cache strong object literal maps

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index ecb5bf1b5164265ae48d7f4be04d01181a7c8c65..674aef56e6b968bf4a2e2530e14a16458f832025 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -9734,6 +9734,7 @@ static bool CheckEquivalent(Map* first, Map* second) {
          first->instance_type() == second->instance_type() &&
          first->bit_field() == second->bit_field() &&
          first->is_extensible() == second->is_extensible() &&
+         first->is_strong() == second->is_strong() &&
          first->has_instance_call_handler() ==
              second->has_instance_call_handler();
 }
@@ -10369,7 +10370,7 @@ void JSFunction::SetInstancePrototype(Handle<JSFunction> function,
         CacheInitialJSArrayMaps(native_context, new_map);
         Handle<Map> new_strong_map =
             Map::Copy(initial_map, "SetInstancePrototype");
-        new_strong_map->set_is_strong(true);
+        new_strong_map->set_is_strong();
         CacheInitialJSArrayMaps(native_context, new_strong_map);
       }
     }