Made PropertyType handling even more explicit.

src/factory.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 826 matching lines @@
       NewDescriptorArray(array->number_of_descriptors() + nof_callbacks);
 
   // Number of descriptors added to the result so far.
   int descriptor_count = 0;
 
   // Ensure that marking will not progress and change color of objects.
   DescriptorArray::WhitenessWitness witness(*result);
 
   // Copy the descriptors from the array.
   for (int i = 0; i < array->number_of_descriptors(); i++) {
-    if (array->GetType(i) != NULL_DESCRIPTOR) {
+    if (!array->IsNullDescriptor(i)) {
       result->CopyFrom(descriptor_count++, *array, i, witness);
     }
   }
 
   // Number of duplicates detected.
   int duplicates = 0;
 
   // Fill in new callback descriptors.  Process the callbacks from
   // back to front so that the last callback with a given name takes
   // precedence over previously added callbacks with that name.
@@ skipping 500 matching lines @@
 
 
 Handle<Object> Factory::ToBoolean(bool value) {
   return Handle<Object>(value
                         ? isolate()->heap()->true_value()
                         : isolate()->heap()->false_value());
 }
 
 
 } }  // namespace v8::internal