[strong] Object literals create strong objects

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 6dc5de2552847c8487da20604452705a7837143f..97f43506b984bfd39194f3633e10d15589d1e726 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -3800,7 +3800,9 @@ Handle<Map> Map::TransitionElementsTo(Handle<Map> map,
 
   Isolate* isolate = map->GetIsolate();
   Context* native_context = isolate->context()->native_context();
-  Object* maybe_array_maps = native_context->js_array_maps();
+  Object* maybe_array_maps = map->is_strong()
+      ? native_context->js_array_strong_maps()
+      : native_context->js_array_maps();
   if (maybe_array_maps->IsFixedArray()) {
     DisallowHeapAllocation no_gc;
     FixedArray* array_maps = FixedArray::cast(maybe_array_maps);
@@ -10288,7 +10290,7 @@ void Map::SetPrototype(Handle<Map> map, Handle<Object> prototype,
 
 
 Handle<Object> CacheInitialJSArrayMaps(
-    Handle<Context> native_context, Handle<Map> initial_map) {
+    Handle<Context> native_context, Handle<Map> initial_map, bool is_strong) {
   // Replace all of the cached initial array maps in the native context with
   // the appropriate transitioned elements kind maps.
   Factory* factory = native_context->GetIsolate()->factory();
@@ -10314,7 +10316,10 @@ Handle<Object> CacheInitialJSArrayMaps(
     maps->set(next_kind, *new_map);
     current_map = new_map;
   }
-  native_context->set_js_array_maps(*maps);
+  if (is_strong)
+    native_context->set_js_array_strong_maps(*maps);
+  else
+    native_context->set_js_array_maps(*maps);
   return initial_map;
 }
 
@@ -10355,7 +10360,14 @@ void JSFunction::SetInstancePrototype(Handle<JSFunction> function,
           native_context->get(Context::ARRAY_FUNCTION_INDEX);
       if (array_function->IsJSFunction() &&
           *function == JSFunction::cast(array_function)) {
-        CacheInitialJSArrayMaps(handle(native_context, isolate), new_map);
+        CacheInitialJSArrayMaps(handle(native_context, isolate), new_map,
+                                false);
+        // Piggy-back this place to also create the strong array maps.
+        Handle<Map> new_strong_map =
+            Map::Copy(initial_map, "SetInstancePrototype");
+        new_strong_map->set_is_strong(true);
+        CacheInitialJSArrayMaps(handle(native_context, isolate),
+                                new_strong_map, true);
       }
     }