Create a transition API for the debug message handler

src/debug.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 528 matching lines @@
                            Handle<JSFunction> fun);
   static void OnNewFunction(Handle<JSFunction> fun);
   static void ProcessDebugEvent(v8::DebugEvent event,
                                 Handle<JSObject> event_data,
                                 bool auto_continue);
   static void NotifyMessageHandler(v8::DebugEvent event,
                                    Handle<JSObject> exec_state,
                                    Handle<JSObject> event_data,
                                    bool auto_continue);
   static void SetEventListener(Handle<Object> callback, Handle<Object> data);
-  static void SetMessageHandler(v8::Debug::MessageHandler handler);
+  static void SetMessageHandler(v8::Debug::MessageHandler2 handler);
   static void SetHostDispatchHandler(v8::Debug::HostDispatchHandler handler,
                                      int period);
 
   // Invoke the message handler function.
   static void InvokeMessageHandler(MessageImpl message);
 
   // Add a debugger command to the command queue.
   static void ProcessCommand(Vector<const uint16_t> command,
                              v8::Debug::ClientData* client_data = NULL);
 
@@ skipping 35 matching lines @@
 
  private:
   static bool IsDebuggerActive();
 
   static Mutex* debugger_access_;  // Mutex guarding debugger variables.
   static Handle<Object> event_listener_;  // Global handle to listener.
   static Handle<Object> event_listener_data_;
   static bool compiling_natives_;  // Are we compiling natives?
   static bool is_loading_debugger_;  // Are we loading the debugger?
   static bool never_unload_debugger_;  // Can we unload the debugger?
-  static v8::Debug::MessageHandler message_handler_;
+  static v8::Debug::MessageHandler2 message_handler_;
   static bool message_handler_cleared_;  // Was message handler cleared?
   static v8::Debug::HostDispatchHandler host_dispatch_handler_;
   static int host_dispatch_micros_;
 
   static DebuggerAgent* agent_;
 
   static const int kQueueInitialSize = 4;
   static LockingCommandMessageQueue command_queue_;
   static Semaphore* command_received_;  // Signaled for each command received.
 
@@ skipping 140 matching lines @@
   Debug::AddressId id_;
   int reg_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_V8_DEBUG_H_