Allow 4 more fast properties for objects.

src/objects.h

 // 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 1716 matching lines @@
   // the number of maps for objects used as dictionaries.
   inline int MaxFastProperties();
 
   // Maximal number of elements (numbered 0 .. kMaxElementCount - 1).
   // Also maximal value of JSArray's length property.
   static const uint32_t kMaxElementCount = 0xffffffffu;
 
   static const uint32_t kMaxGap = 1024;
   static const int kMaxFastElementsLength = 5000;
   static const int kInitialMaxFastElementArray = 100000;
-  static const int kMaxFastProperties = 8;
+  static const int kMaxFastProperties = 12;
   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;
   static const int kHeaderSize = kElementsOffset + kPointerSize;
@@ skipping 4600 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_