Implement issue 549 Make V8 call DebugMessageDispatchHandler with Locker locked

include/v8-debug.h

Index: include/v8-debug.h
diff --git a/include/v8-debug.h b/include/v8-debug.h
index ff3182ca989a699b3d3f358aa3b582501c4d816e..2e5fb3fde9eb90eb9f74a639652bb0e401efd65c 100644
--- a/include/v8-debug.h
+++ b/include/v8-debug.h
@@ -224,9 +224,11 @@ class EXPORT Debug {
    * be processed. Note that debug messages will only be processed if there is
    * a V8 break. This can happen automatically by using the option
    * --debugger-auto-break.
+   * \param provide_locker requires that V8 acquires v8::Locker for you before
+   *        calling handler
    */
   static void SetDebugMessageDispatchHandler(
-      DebugMessageDispatchHandler handler);
+      DebugMessageDispatchHandler handler, bool provide_locker = false);
 
  /**
   * Run a JavaScript function in the debugger.