In-place shrinking of descriptor arrays with non-live transitions.

src/property.h

 // 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 155 matching lines @@
       Object* callback_object = desc->GetCallbackObject();
       // Non-JavaScript (i.e. native) accessors are always a property, otherwise
       // either the getter or the setter must be an accessor. Put another way:
       // If we only see map transitions and holes in a pair, this is not a
       // property.
       return (!callback_object->IsAccessorPair() ||
               AccessorPair::cast(callback_object)->ContainsAccessor());
     }
     case MAP_TRANSITION:
     case CONSTANT_TRANSITION:
-    case NULL_DESCRIPTOR:
       return false;
+    case NONEXISTENT:
+      UNREACHABLE();
+      break;
   }
   UNREACHABLE();  // keep the compiler happy
   return false;
 }
 
 
 class LookupResult BASE_EMBEDDED {
  public:
   explicit LookupResult(Isolate* isolate)
       : isolate_(isolate),
@@ skipping 195 matching lines @@
   JSReceiver* holder_;
   int number_;
   bool cacheable_;
   PropertyDetails details_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_H_