Never let the hole escape...

src/objects.cc

 // Copyright 2012 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 4676 matching lines @@
          obj != heap->null_value();
          obj = JSObject::cast(obj)->GetPrototype()) {
       JSObject* js_object = JSObject::cast(obj);
       if (js_object->HasDictionaryElements()) {
         SeededNumberDictionary* dictionary = js_object->element_dictionary();
         int entry = dictionary->FindEntry(index);
         if (entry != SeededNumberDictionary::kNotFound) {
           Object* element = dictionary->ValueAt(entry);
           if (dictionary->DetailsAt(entry).type() == CALLBACKS &&
               element->IsAccessorPair()) {
-            return AccessorPair::cast(element)->get(component);
+            return AccessorPair::cast(element)->SafeGet(component);
           }
         }
       }
     }
   } else {
     for (Object* obj = this;
          obj != heap->null_value();
          obj = JSObject::cast(obj)->GetPrototype()) {
       LookupResult result(heap->isolate());
       JSObject::cast(obj)->LocalLookup(name, &result);
       if (result.IsProperty()) {
         if (result.IsReadOnly()) return heap->undefined_value();
         if (result.type() == CALLBACKS) {
           Object* obj = result.GetCallbackObject();
           if (obj->IsAccessorPair()) {
-            return AccessorPair::cast(obj)->get(component);
+            return AccessorPair::cast(obj)->SafeGet(component);
           }
         }
       }
     }
   }
   return heap->undefined_value();
 }
 
 
 Object* JSObject::SlowReverseLookup(Object* value) {
@@ skipping 1216 matching lines @@
   AccessorPair* copy;
   { MaybeObject* maybe_copy = heap->AllocateAccessorPair();
     if (!maybe_copy->To(&copy)) return maybe_copy;
   }
   copy->set_getter(getter()->IsMap() ? heap->the_hole_value() : getter());
   copy->set_setter(setter()->IsMap() ? heap->the_hole_value() : setter());
   return copy;
 }
 
 
+Object* AccessorPair::SafeGet(AccessorComponent component) {
+    Object* accessor = get(component);
+    return accessor->IsTheHole() ? GetHeap()->undefined_value() : accessor;
+}
+
+
 MaybeObject* DeoptimizationInputData::Allocate(int deopt_entry_count,
                                                PretenureFlag pretenure) {
   ASSERT(deopt_entry_count > 0);
   return HEAP->AllocateFixedArray(LengthFor(deopt_entry_count),
                                   pretenure);
 }
 
 
 MaybeObject* DeoptimizationOutputData::Allocate(int number_of_deopt_points,
                                                 PretenureFlag pretenure) {
@@ skipping 6997 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single break point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal