Make a metaprogramming hack more C++11-compatible

Source/wtf/MemoryInstrumentation.h

 /*
  * Copyright (C) 2012 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 120 matching lines @@
         };
 
         struct BaseMixin {
             void reportMemoryUsage(MemoryObjectInfo*) const { }
         };
 
 #if COMPILER(MSVC)
 #pragma warning(push)
 #pragma warning(disable: 4624) // Disable warning: destructor could not be generated because a base class destructor is inaccessible.
 #endif
-        struct Base : public Type, public BaseMixin { };
+        struct Base : public Type, public BaseMixin {
+          ~Base() {}
+        };
 #if COMPILER(MSVC)
 #pragma warning(pop)
 #endif
 
         template <typename T, T t> class Helper { };
 
         template <typename U> static no deduce(U*, Helper<void (BaseMixin::*)(MemoryObjectInfo*) const, &U::reportMemoryUsage>* = 0);
         static yes deduce(...);
 
     public:
@@ skipping 206 matching lines @@
 
 class ParsedURL;
 void reportMemoryUsage(const ParsedURL*, MemoryObjectInfo*);
 
 class URLString;
 void reportMemoryUsage(const URLString*, MemoryObjectInfo*);
 
 } // namespace WTF
 
 #endif // !defined(MemoryInstrumentation_h)