Tried using CrossThreadPersistent for workerDebuggerAgents

Source/core/inspector/InspectorInstrumentation.h

 /*
 * Copyright (C) 2010 Google Inc. 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
@@ skipping 63 matching lines @@
     InspectorInstrumentationCookie(InstrumentingAgents*, int);
     InspectorInstrumentationCookie(const InspectorInstrumentationCookie&);
     InspectorInstrumentationCookie& operator=(const InspectorInstrumentationCookie&);
     ~InspectorInstrumentationCookie();
 
     InstrumentingAgents* instrumentingAgents() const { return m_instrumentingAgents.get(); }
     bool isValid() const { return !!m_instrumentingAgents; }
     bool hasMatchingTimelineAgentId(int id) const { return m_timelineAgentId == id; }
 
 private:
-    RefPtr<InstrumentingAgents> m_instrumentingAgents;
+    RefPtrWillBePersistent<InstrumentingAgents> m_instrumentingAgents;
     int m_timelineAgentId;
 };
 
 namespace InspectorInstrumentation {
 
 class FrontendCounter {
 private:
     friend void frontendCreated();
     friend void frontendDeleted();
     friend bool hasFrontends();
@@ skipping 96 matching lines @@
 } // namespace WebCore
 
 // This file will soon be generated
 #include "InspectorInstrumentationInl.h"
 
 #include "InspectorInstrumentationCustomInl.h"
 
 #include "InspectorOverridesInl.h"
 
 #endif // !defined(InspectorInstrumentation_h)