Purge UnspecifiedBoolType from Blink.

third_party/WebKit/Source/wtf/RetainPtr.h

 /*
  *  Copyright (C) 2005, 2006, 2007, 2008, 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 88 matching lines @@
 
     template <typename U> RetainPtr(const RetainPtr<U>&);
 
     void clear();
     PtrType leakRef() WARN_UNUSED_RETURN;
 
     PtrType get() const { return m_ptr; }
     PtrType operator->() const { return m_ptr; }
 
     bool operator!() const { return !m_ptr; }
-
-    // This conversion operator allows implicit conversion to bool but not to
-    // other integer types.
-    typedef PtrType RetainPtr::*UnspecifiedBoolType;
-    operator UnspecifiedBoolType() const { return m_ptr ? &RetainPtr::m_ptr : 0; }
+    explicit operator bool() const { return m_ptr; }
 
     RetainPtr& operator=(const RetainPtr&);
     template <typename U> RetainPtr& operator=(const RetainPtr<U>&);
     RetainPtr& operator=(PtrType);
     template <typename U> RetainPtr& operator=(U*);
 
     RetainPtr& operator=(RetainPtr&&);
     template <typename U> RetainPtr& operator=(RetainPtr<U>&&);
 
     RetainPtr& operator=(std::nullptr_t)
@@ skipping 196 matching lines @@
 } // namespace WTF
 
 using WTF::AdoptCF;
 using WTF::AdoptNS;
 using WTF::adoptCF;
 using WTF::adoptNS;
 using WTF::RetainPtr;
 using WTF::retainPtr;
 
 #endif // WTF_RetainPtr_h