Use null instead of undefined for deleted elements in code caches....

src/ic.cc

 // 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 146 matching lines @@
     // invalid stub again.
     map->RemoveFromCodeCache(index);
 
     return MONOMORPHIC_PROTOTYPE_FAILURE;
   }
 
   // The builtins object is special.  It only changes when JavaScript
   // builtins are loaded lazily.  It is important to keep inline
   // caches for the builtins object monomorphic.  Therefore, if we get
   // an inline cache miss for the builtins object after lazily loading
-  // JavaScript builtins, we clear the code cache and return
-  // uninitialized as the state to force the inline cache back to
-  // monomorphic state.
+  // JavaScript builtins, we return uninitialized as the state to
+  // force the inline cache back to monomorphic state.
   if (receiver->IsJSBuiltinsObject()) {
-    map->ClearCodeCache();
     return UNINITIALIZED;
   }
 
   return MONOMORPHIC;
 }
 
 
 RelocMode IC::ComputeMode() {
   Address addr = address();
   Code* code = Code::cast(Heap::FindCodeObject(addr));
@@ skipping 973 matching lines @@
 #undef ADDR
 };
 
 
 Address IC::AddressFromUtilityId(IC::UtilityId id) {
   return IC_utilities[id];
 }
 
 
 } }  // namespace v8::internal