Removed the debug message thread

src/v8.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 95 matching lines @@
   }
 
   Builtins::TearDown();
   Bootstrapper::TearDown();
 
   Top::TearDown();
 
   Heap::TearDown();
   Logger::TearDown();
 
-#ifdef ENABLE_DEBUGGER_SUPPORT
-  Debugger::TearDown();
-#endif
-
   has_been_setup_ = false;
   has_been_disposed_ = true;
 }
 
 } }  // namespace v8::internal