RefCounted::derefBase() should do the decrement from 1 to 0

Source/wtf/RefCounted.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 100 matching lines @@
     // Returns whether the pointer should be freed or not.
     bool derefBase()
     {
         ASSERT_WITH_SECURITY_IMPLICATION(!m_deletionHasBegun);
 #if CHECK_REF_COUNTED_LIFECYCLE
         ASSERT(m_verifier.isSafeToUse());
         ASSERT(!m_adoptionIsRequired);
 #endif
 
         ASSERT(m_refCount > 0);
-        if (m_refCount == 1) {
+        --m_refCount;
+        if (!m_refCount) {
 #if SECURITY_ASSERT_ENABLED
             m_deletionHasBegun = true;
 #endif
             return true;
         }
 
-        --m_refCount;
 #if CHECK_REF_COUNTED_LIFECYCLE
         // Stop thread verification when the ref goes to 1 because it
         // is safe to be passed to another thread at this point.
         if (m_refCount == 1)
             m_verifier.setShared(false);
 #endif
         return false;
     }
 
 #if CHECK_REF_COUNTED_LIFECYCLE
@@ skipping 58 matching lines @@
     {
     }
 #endif
 };
 
 } // namespace WTF
 
 using WTF::RefCounted;
 
 #endif // RefCounted_h