Fixed some cctest flakiness on mac.

src/debug.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 2480 matching lines @@
 void Debugger::StopAgent() {
   if (agent_ != NULL) {
     agent_->Shutdown();
     agent_->Join();
     delete agent_;
     agent_ = NULL;
   }
 }
 
 
+void Debugger::WaitForAgent() {
+  if (agent_ != NULL)
+    agent_->WaitUntilListening();
+}
+
 MessageImpl MessageImpl::NewEvent(DebugEvent event,
                                   bool running,
                                   Handle<JSObject> exec_state,
                                   Handle<JSObject> event_data) {
   MessageImpl message(true, event, running,
                       exec_state, event_data, Handle<String>(), NULL);
   return message;
 }
 
 
@@ skipping 203 matching lines @@
 
 
 void LockingCommandMessageQueue::Clear() {
   ScopedLock sl(lock_);
   queue_.Clear();
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal