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

Source/core/inspector/TraceEventDispatcher.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 88 matching lines @@
 }
 
 void TraceEventDispatcher::innerAddListener(const char* name, char phase, TraceEventTargetBase* instance, TraceEventHandlerMethod method, InspectorClient* client)
 {
     ASSERT(isMainThread());
     MutexLocker locker(m_mutex);
     if (m_handlers.isEmpty())
         client->setTraceEventCallback(dispatchEventOnAnyThread);
     HandlersMap::iterator it = m_handlers.find(std::make_pair(name, phase));
     if (it == m_handlers.end())
-        it = m_handlers.add(std::make_pair(name, phase), Vector<BoundTraceEventHandler>()).iterator;
-    it->value.append(BoundTraceEventHandler(instance, method));
+        m_handlers.add(std::make_pair(name, phase), Vector<BoundTraceEventHandler>()).iterator->value.append(BoundTraceEventHandler(instance, method));
+    else
+        it->value.append(BoundTraceEventHandler(instance, method));
 }
 
 void TraceEventDispatcher::removeAllListeners(TraceEventTargetBase* instance, InspectorClient* client)
 {
     ASSERT(isMainThread());
     processBackgroundEvents();
     {
         MutexLocker locker(m_mutex);
 
         HandlersMap remainingHandlers;
@@ skipping 29 matching lines @@
     size_t index = findParameter(name);
     if (index == kNotFound || m_argumentTypes[index] != expectedType) {
         ASSERT_NOT_REACHED();
         return missingValue;
     }
     return *reinterpret_cast<const WebCore::TraceEvent::TraceValueUnion*>(m_argumentValues + index);
 }
 
 } // namespace WebCore