Simpler return value of HashTable::add/HashMap:add and others

Source/wtf/InstanceCounter.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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 78 matching lines @@
 String dumpRefCountedInstanceCounts()
 {
     return InstanceCounter::instance()->dump();
 }
 
 void InstanceCounter::incrementInstanceCount(const String& instanceName, void* ptr)
 {
     MutexLocker locker(m_mutex);
     HashMap<String, int>::AddResult result = m_counterMap.add(instanceName, 1);
     if (!result.isNewEntry)
-        ++(result.iterator->value);
+        ++(result.storedValue->value);
 }
 
 void InstanceCounter::decrementInstanceCount(const String& instanceName, void* ptr)
 {
     MutexLocker locker(m_mutex);
     HashMap<String, int>::iterator it = m_counterMap.find(instanceName);
     ASSERT(it != m_counterMap.end());
 
     --(it->value);
     if (!it->value)
@@ skipping 25 matching lines @@
 #else
 
 String dumpRefCountedInstanceCounts()
 {
     return String("{}");
 }
 
 #endif // ENABLE_INSTANCE_COUNTER
 
 } // namespace WTF