[DevTools] Clear DatabaseClient's pointer to InspectorDatabaseAgent on detach.

Source/modules/webdatabase/DatabaseClient.cpp

 /*
  * Copyright (C) 2013 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 52 matching lines @@
 }
 
 void DatabaseClient::didOpenDatabase(Database* database, const String& domain, const String& name, const String& version)
 {
     if (m_inspectorAgent)
         m_inspectorAgent->didOpenDatabase(database, domain, name, version);
 }
 
 void DatabaseClient::setInspectorAgent(InspectorDatabaseAgent* agent)
 {
-    ASSERT(!m_inspectorAgent);
+    // TODO(dgozman): we should not set agent twice, but it's happening in OOPIF case.
     m_inspectorAgent = agent;
 }
 
 void provideDatabaseClientTo(Page& page, PassOwnPtrWillBeRawPtr<DatabaseClient> client)
 {
     page.provideSupplement(DatabaseClient::supplementName(), client);
 }
 
 } // namespace blink