Reapply 169371 "DevTools: defer styles delta calculation to until the end of the task"

Source/core/inspector/InspectorBaseAgent.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 76 matching lines @@
     for (size_t i = 0; i < m_agents.size(); i++)
         m_agents[i]->registerInDispatcher(dispatcher);
 }
 
 void InspectorAgentRegistry::discardAgents()
 {
     for (size_t i = 0; i < m_agents.size(); i++)
         m_agents[i]->discardAgent();
 }
 
+void InspectorAgentRegistry::flushPendingFrontendMessages()
+{
+    for (size_t i = 0; i < m_agents.size(); i++)
+        m_agents[i]->flushPendingFrontendMessages();
+}
+
 } // namespace WebCore