Make sure that we don't actually overwrite a property that has failed access ...

src/runtime.cc

 // Copyright 2010 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 823 matching lines @@
   }
 
   // Use recursive implementation to also traverse hidden prototypes
   GetOwnPropertyImplementation(*obj, *name, &result);
 
   if (!result.IsProperty()) {
     return Heap::undefined_value();
   }
 
   if (!CheckAccess(*obj, *name, &result, v8::ACCESS_HAS)) {
-    return Heap::undefined_value();
+    return Heap::false_value();
   }
 
   elms->set(ENUMERABLE_INDEX, Heap::ToBoolean(!result.IsDontEnum()));
   elms->set(CONFIGURABLE_INDEX, Heap::ToBoolean(!result.IsDontDelete()));
 
   bool is_js_accessor = (result.type() == CALLBACKS) &&
                         (result.GetCallbackObject()->IsFixedArray());
 
   if (is_js_accessor) {
     // __defineGetter__/__defineSetter__ callback.
@@ skipping 10175 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal