Debugger: remove debug command API.

include/v8-debug.h

Index: include/v8-debug.h
diff --git a/include/v8-debug.h b/include/v8-debug.h
index ae11a2aeea74fa7aa002296ccbb7d849081aed53..6e90a1c89812c80117571a085329629371740098 100644
--- a/include/v8-debug.h
+++ b/include/v8-debug.h
@@ -170,13 +170,6 @@ class V8_EXPORT Debug {
   // Check if a debugger break is scheduled in the given isolate.
   static bool CheckDebugBreak(Isolate* isolate);
 
-  // Break execution of JavaScript in the given isolate (this method
-  // can be invoked from a non-VM thread) for further client command
-  // execution on a VM thread. Client data is then passed in
-  // EventDetails to EventCallback2 at the moment when the VM actually
-  // stops.
-  static void DebugBreakForCommand(Isolate* isolate, ClientData* data);
-
   // Message based interface. The message protocol is JSON.
   static void SetMessageHandler(MessageHandler handler);