Reapply "wait for connection" feature implementation

src/debug.h

Index: src/debug.h
diff --git a/src/debug.h b/src/debug.h
index 24f0db4133d26986c0823d0f624c63fdf82ece5b..c37e08b38f357dd3070ec866360b6bf9cb24aaa2 100644
--- a/src/debug.h
+++ b/src/debug.h
@@ -636,7 +636,8 @@ class Debugger {
                              bool* pending_exception);
 
   // Start the debugger agent listening on the provided port.
-  static bool StartAgent(const char* name, int port);
+  static bool StartAgent(const char* name, int port,
+                         bool wait_for_connection = false);
 
   // Stop the debugger agent.
   static void StopAgent();