Fix crash in Debug::SendCommand.

include/v8-debug.h

 // Copyright 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 258 matching lines @@
   // EventDetails to EventCallback at the moment when the VM actually
   // stops. If no isolate is provided the default isolate is used.
   static void DebugBreakForCommand(ClientData* data = NULL,
                                    Isolate* isolate = NULL);
 
   // Message based interface. The message protocol is JSON. NOTE the message
   // handler thread is not supported any more parameter must be false.
   static void SetMessageHandler(MessageHandler handler,
                                 bool message_handler_thread = false);
   static void SetMessageHandler2(MessageHandler2 handler);
+
+  // If no isolate is provided the default isolate is
+  // used.
   static void SendCommand(const uint16_t* command, int length,
-                          ClientData* client_data = NULL);
+                          ClientData* client_data = NULL,
+                          Isolate* isolate = NULL);
 
   // Dispatch interface.
   static void SetHostDispatchHandler(HostDispatchHandler handler,
                                      int period = 100);
 
   /**
    * Register a callback function to be called when a debug message has been
    * received and is ready to be processed. For the debug messages to be
    * processed V8 needs to be entered, and in certain embedding scenarios this
    * callback can be used to make sure V8 is entered for the debug message to
@@ skipping 90 matching lines @@
 };
 
 
 }  // namespace v8
 
 
 #undef EXPORT
 
 
 #endif  // V8_V8_DEBUG_H_