Put zapping of local handles behind the extra checks flag.

src/handles.cc

 // Copyright 2012 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 83 matching lines @@
 }
 
 
 void HandleScope::DeleteExtensions(Isolate* isolate) {
   v8::ImplementationUtilities::HandleScopeData* current =
       isolate->handle_scope_data();
   isolate->handle_scope_implementer()->DeleteExtensions(current->limit);
 }
 
 
+#ifdef ENABLE_EXTRA_CHECKS
 void HandleScope::ZapRange(Object** start, Object** end) {
   ASSERT(end - start <= kHandleBlockSize);
   for (Object** p = start; p != end; p++) {
     *reinterpret_cast<Address*>(p) = v8::internal::kHandleZapValue;
   }
 }
+#endif
 
 
 Address HandleScope::current_level_address(Isolate* isolate) {
   return reinterpret_cast<Address>(&isolate->handle_scope_data()->level);
 }
 
 
 Address HandleScope::current_next_address(Isolate* isolate) {
   return reinterpret_cast<Address>(&isolate->handle_scope_data()->next);
 }
@@ skipping 808 matching lines @@
   data->next = prev_next_;
   data->limit = prev_limit_;
 #ifdef DEBUG
   handles_detached_ = true;
 #endif
   return deferred;
 }
 
 
 } }  // namespace v8::internal