Arrays created with new Array(n) are not assumed to be sparse unless the give...

src/objects.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 1415 matching lines @@
     int number_of_slow_used_elements_;
     int number_of_slow_unused_elements_;
   };
 
   void IncrementSpillStatistics(SpillInformation* info);
 #endif
   Object* SlowReverseLookup(Object* value);
 
   static const uint32_t kMaxGap = 1024;
   static const int kMaxFastElementsLength = 5000;
+  static const int kInitialMaxFastElementArray = 100000;
   static const int kMaxFastProperties = 8;
   static const int kMaxInstanceSize = 255 * kPointerSize;
   // When extending the backing storage for property values, we increase
   // its size by more than the 1 entry necessary, so sequentially adding fields
   // to the same object requires fewer allocations and copies.
   static const int kFieldsAdded = 3;
 
   // Layout description.
   static const int kPropertiesOffset = HeapObject::kHeaderSize;
   static const int kElementsOffset = kPropertiesOffset + kPointerSize;
@@ skipping 2833 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_