Object.defineProperty shouldn't be a hint that we're constructing a dictionary.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 27335933cad546a24b50080c045baa38f4388a32..cc92c682ad27a4b3f56fba5e7bbedaebff948d13 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -4318,7 +4318,8 @@ MaybeHandle<Object> JSObject::SetLocalPropertyIgnoreAttributes(
     PropertyAttributes attributes,
     ValueType value_type,
     StoreMode mode,
-    ExtensibilityCheck extensibility_check) {
+    ExtensibilityCheck extensibility_check,
+    StoreFromKeyed store_from_keyed) {
   Isolate* isolate = object->GetIsolate();
 
   // Make sure that the top context does not change when doing callbacks or
@@ -4359,7 +4360,7 @@ MaybeHandle<Object> JSObject::SetLocalPropertyIgnoreAttributes(
         ? OMIT_TRANSITION : INSERT_TRANSITION;
     // Neither properties nor transitions found.
     return AddProperty(object, name, value, attributes, SLOPPY,
-        MAY_BE_STORE_FROM_KEYED, extensibility_check, value_type, mode, flag);
+        store_from_keyed, extensibility_check, value_type, mode, flag);
   }
 
   Handle<Object> old_value = isolate->factory()->the_hole_value();