Fix issue with Array.concat not preserving holes in the

src/factory.h

 // Copyright 2006-2008 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 19 matching lines @@
 
 #include "heap.h"
 
 namespace v8 { namespace internal {
 
 
 // Interface for handle based allocation.
 
 class Factory : public AllStatic {
  public:
-  // Allocate a new fixed array.
+  // Allocate a new fixed array with undefined entries.
   static Handle<FixedArray> NewFixedArray(
       int size,
       PretenureFlag pretenure = NOT_TENURED);
+
+  // Allocate a new fixed array with non-existing entries (the hole).
+  static Handle<FixedArray> NewFixedArrayWithHoles(int size);
+
   static Handle<Dictionary> NewDictionary(int at_least_space_for);
 
   static Handle<DescriptorArray> NewDescriptorArray(int number_of_descriptors);
 
   static Handle<String> LookupSymbol(Vector<const char> str);
   static Handle<String> LookupAsciiSymbol(const char* str) {
     return LookupSymbol(CStrVector(str));
   }
 
 
@@ skipping 281 matching lines @@
   // Update the map cache in the global context with (keys, map)
   static Handle<MapCache> AddToMapCache(Handle<Context> context,
                                         Handle<FixedArray> keys,
                                         Handle<Map> map);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_FACTORY_H_