DevTools: Add an ASSERT to explore possible reasons of test failures.

Source/core/inspector/InspectorWorkerAgent.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 41 matching lines @@
 
 class InspectorWorkerAgent::WorkerFrontendChannel FINAL : public WorkerInspectorProxy::PageInspector {
     WTF_MAKE_FAST_ALLOCATED;
 public:
     explicit WorkerFrontendChannel(InspectorFrontend::Worker* frontend, WorkerInspectorProxy* proxy)
         : m_frontend(frontend)
         , m_proxy(proxy)
         , m_id(s_nextId++)
         , m_connected(false)
     {
+        ASSERT(!proxy->pageInspector());
     }
     virtual ~WorkerFrontendChannel()
     {
         disconnectFromWorker();
     }
 
     int id() const { return m_id; }
     WorkerInspectorProxy* proxy() const { return m_proxy; }
 
     void connectToWorker()
@@ skipping 185 matching lines @@
     m_idToChannel.set(channel->id(), channel);
 
     ASSERT(m_frontend);
     bool autoconnectToWorkers = m_state->getBoolean(WorkerAgentState::autoconnectToWorkers);
     if (autoconnectToWorkers)
         channel->connectToWorker();
     m_frontend->workerCreated(channel->id(), url, autoconnectToWorkers);
 }
 
 } // namespace blink