Oilpan: Prepare moving InspectorAgent related classes to oilpan

Source/core/inspector/WorkerInspectorController.cpp

 /*
  * Copyright (C) 2011 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 158 matching lines @@
 void WorkerInspectorController::discard()
 {
     m_debuggerAgent->discard();
     m_debuggerAgent = nullptr;
     m_instrumentingAgents->reset();
     disconnectFrontend();
 }
 
 void WorkerInspectorController::trace(Visitor* visitor)
 {
+    visitor->trace(m_instrumentingAgents);
     visitor->trace(m_agents);
     visitor->trace(m_debuggerAgent);
 }
 
 }