Confusion on changing data property callback attributes

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 68a730bb6643bb426f0576fbbaf15911b50a3360..c5b60e91d2aec12f1ac3ba354bb9982938967aec 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -5175,26 +5175,6 @@ RUNTIME_FUNCTION(Runtime_DefineOrRedefineDataProperty) {
   LookupResult lookup(isolate);
   js_object->LookupOwnRealNamedProperty(name, &lookup);
 
-  // Special case for callback properties.
-  if (lookup.IsPropertyCallbacks()) {
-    Handle<Object> callback(lookup.GetCallbackObject(), isolate);
-    // Avoid redefining callback as data property, just use the stored
-    // setter to update the value instead.
-    // TODO(mstarzinger): So far this only works if property attributes don't
-    // change, this should be fixed once we cleanup the underlying code.
-    ASSERT(!callback->IsForeign());
-    if (callback->IsAccessorInfo() &&
-        lookup.GetAttributes() == attr) {
-      Handle<Object> result_object;
-      ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-          isolate, result_object,
-          JSObject::SetPropertyWithCallback(js_object, name, obj_value,
-                                            handle(lookup.holder()),
-                                            callback, STRICT));
-      return *result_object;
-    }
-  }
-
   // Take special care when attributes are different and there is already
   // a property. For simplicity we normalize the property which enables us
   // to not worry about changing the instance_descriptor and creating a new
@@ -5209,14 +5189,25 @@ RUNTIME_FUNCTION(Runtime_DefineOrRedefineDataProperty) {
       // we don't have to check for null.
       js_object = Handle<JSObject>(JSObject::cast(js_object->GetPrototype()));
     }
-    JSObject::NormalizeProperties(js_object, CLEAR_INOBJECT_PROPERTIES, 0);
+
+    if (attr != lookup.GetAttributes() ||
+        (lookup.IsPropertyCallbacks() &&
+         !lookup.GetCallbackObject()->IsAccessorInfo())) {
+      JSObject::NormalizeProperties(js_object, CLEAR_INOBJECT_PROPERTIES, 0);
+    }
+
     // Use IgnoreAttributes version since a readonly property may be
     // overridden and SetProperty does not allow this.
     Handle<Object> result;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, result,
         JSObject::SetOwnPropertyIgnoreAttributes(
-            js_object, name, obj_value, attr));
+            js_object, name, obj_value, attr,
+            Object::OPTIMAL_REPRESENTATION,
+            ALLOW_AS_CONSTANT,
+            JSReceiver::PERFORM_EXTENSIBILITY_CHECK,
+            JSReceiver::MAY_BE_STORE_FROM_KEYED,
+            JSObject::DONT_FORCE_FIELD));
     return *result;
   }