Avoid map transitions and multiple backing arrays for builtin prototypes...

src/runtime.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 229 matching lines @@
   F(LoadContextSlot, 2) \
   F(LoadContextSlotNoReferenceError, 2) \
   F(StoreContextSlot, 3) \
   \
   /* Declarations and initialization */ \
   F(DeclareGlobals, 3) \
   F(DeclareContextSlot, 4) \
   F(InitializeVarGlobal, -1 /* 1 or 2 */) \
   F(InitializeConstGlobal, 2) \
   F(InitializeConstContextSlot, 3) \
+  F(OptimizeObjectForAddingMultipleProperties, 2) \
+  F(TransformToFastProperties, 1) \
   \
   /* Debugging */ \
   F(DebugPrint, 1) \
   F(DebugTrace, 0) \
   F(TraceEnter, 0) \
   F(TraceExit, 1) \
   F(Abort, 2) \
   /* Logging */ \
   F(Log, 2) \
   \
@@ skipping 133 matching lines @@
                                                 int position);
 
   // Helper functions used stubs.
   static void PerformGC(Object* result);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_RUNTIME_H_