Fixed some cctest flakiness on mac.

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 627 matching lines @@
   static Handle<Object> Call(Handle<JSFunction> fun,
                              Handle<Object> data,
                              bool* pending_exception);
 
   // Start the debugger agent listening on the provided port.
   static bool StartAgent(const char* name, int port);
 
   // Stop the debugger agent.
   static void StopAgent();
 
+  // Blocks until the agent has started listening for connections
+  static void WaitForAgent();
+
   // Unload the debugger if possible. Only called when no debugger is currently
   // active.
   static void UnloadDebugger();
 
   inline static bool EventActive(v8::DebugEvent event) {
     ScopedLock with(debugger_access_);
 
     // Check whether the message handler was been cleared.
     if (debugger_unload_pending_) {
       UnloadDebugger();
@@ skipping 198 matching lines @@
   Debug::AddressId id_;
   int reg_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 #endif  // V8_DEBUG_H_