Prevent recursion in the debug event listener.

src/debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/arguments.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 2744 matching lines @@
       command.Dispose();
     }
   }
 }
 
 
 void Debug::CallEventCallback(v8::DebugEvent event,
                               Handle<Object> exec_state,
                               Handle<Object> event_data,
                               v8::Debug::ClientData* client_data) {
+  DisableBreak no_break(this, true);
   if (event_listener_->IsForeign()) {
     // Invoke the C debug event listener.
     v8::Debug::EventCallback callback =
         FUNCTION_CAST<v8::Debug::EventCallback>(
             Handle<Foreign>::cast(event_listener_)->foreign_address());
     EventDetailsImpl event_details(event,
                                    Handle<JSObject>::cast(exec_state),
                                    Handle<JSObject>::cast(event_data),
                                    event_listener_data_,
                                    client_data);
@@ skipping 610 matching lines @@
   logger_->DebugEvent("Put", message.text());
 }
 
 
 void LockingCommandMessageQueue::Clear() {
   base::LockGuard<base::Mutex> lock_guard(&mutex_);
   queue_.Clear();
 }
 
 } }  // namespace v8::internal