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 116 matching lines @@
         };
 
         class no {
             yes m[2];
         };
 
         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 { };
-#if COMPILER(MSVC)
-#pragma warning(pop)
-#endif
+        struct Base : public Type, public BaseMixin {
+            // Provide expicit destructor without definition to avoid MSVC warning "destructor could
+            // not be generated because a base class destructor is inaccessible."
+            ~Base();
+        };
 
         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:
         static const bool result = sizeof(yes) == sizeof(deduce((Base*)(0)));
 
     };
@@ skipping 203 matching lines @@
 
 class ParsedURL;
 void reportMemoryUsage(const ParsedURL*, MemoryObjectInfo*);
 
 class URLString;
 void reportMemoryUsage(const URLString*, MemoryObjectInfo*);
 
 } // namespace WTF
 
 #endif // !defined(MemoryInstrumentation_h)