(Concept patch) Simplify WTF::HashTable::add() return value for size and performance

Source/core/inspector/AsyncCallStackTracker.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 62 matching lines @@
         ASSERT(executionContext());
         ExecutionContextData* self = m_tracker->m_executionContextDataMap.take(executionContext());
         ASSERT(self == this);
         ContextLifecycleObserver::contextDestroyed();
         delete self;
     }
 
     void addEventListenerData(EventTarget* eventTarget, const AtomicString& eventType, const EventListenerAsyncCallChain& item)
     {
         HashMap<EventTarget*, EventListenerAsyncCallChainVectorHashMap>::iterator it = m_eventTargetCallChains.find(eventTarget);
+        EventListenerAsyncCallChainVectorHashMap* mapPtr;
         if (it == m_eventTargetCallChains.end())
-            it = m_eventTargetCallChains.set(eventTarget, EventListenerAsyncCallChainVectorHashMap()).iterator;
-        EventListenerAsyncCallChainVectorHashMap& map = it->value;
+            mapPtr = &m_eventTargetCallChains.set(eventTarget, EventListenerAsyncCallChainVectorHashMap()).iterator->value;
+        else
+            mapPtr = &it->value;
+        EventListenerAsyncCallChainVectorHashMap& map = *mapPtr;
         EventListenerAsyncCallChainVectorHashMap::iterator it2 = map.find(eventType);
         if (it2 == map.end())
-            it2 = map.set(eventType, EventListenerAsyncCallChainVector()).iterator;
-        it2->value.append(item);
+            map.set(eventType, EventListenerAsyncCallChainVector()).iterator->value.append(item);
+        else
+            it2->value.append(item);
     }
 
     void removeEventListenerData(EventTarget* eventTarget, const AtomicString& eventType, const RegisteredEventListener& item)
     {
         findEventListenerData(eventTarget, eventType, item, true);
     }
 
     PassRefPtr<AsyncCallChain> findEventListenerData(EventTarget* eventTarget, const AtomicString& eventType, const RegisteredEventListener& item, bool remove = false)
     {
         HashMap<EventTarget*, EventListenerAsyncCallChainVectorHashMap>::iterator it = m_eventTargetCallChains.find(eventTarget);
@@ skipping 348 matching lines @@
 {
     m_currentAsyncCallChain.clear();
     m_nestedAsyncCallCount = 0;
     ExecutionContextDataMap copy;
     m_executionContextDataMap.swap(copy);
     for (ExecutionContextDataMap::const_iterator it = copy.begin(); it != copy.end(); ++it)
         delete it->value;
 }
 
 } // namespace WebCore