Prevent recursive exception notification in debugger

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
===================================================================
--- runtime/vm/debugger.cc	(revision 25959)
+++ runtime/vm/debugger.cc	(working copy)
@@ -1064,11 +1064,13 @@
   ASSERT(stack_trace_ == NULL);
   stack_trace_ = stack_trace;
   ASSERT(obj_cache_ == NULL);
+  in_event_notification_ = true;
   obj_cache_ = new RemoteObjectCache(64);
   DebuggerEvent event;
   event.type = kExceptionThrown;
   event.exception = &exc;
   (*event_handler_)(&event);

[Ivan Posva, 2013/08/09 16:31:34]

I think we should abstract the dispatch to the event handler out and have that
set and reset the in_event_notification status. That way all of the other,
currently unprotected, event_handler calls will automatically be protected from
similar issues.

+  in_event_notification_ = false;
   stack_trace_ = NULL;
   obj_cache_ = NULL;  // Remote object cache is zone allocated.
 }