Make sure all destructors are called in HeapHashMap and HeapHashSet

Source/wtf/DefaultAllocator.h

 /*
  * 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:
  *
  *     * 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 48 matching lines @@
 
 class DefaultAllocator {
 public:
     typedef DefaultAllocatorQuantizer Quantizer;
     typedef DefaultAllocatorDummyVisitor Visitor;
     static const bool isGarbageCollected = false;
     template<typename T, typename Traits>
     struct VectorBackingHelper {
         typedef void Type;
     };
-    template<typename T, typename U, typename V, typename W, typename X>
+    template<typename T>
     struct HashTableBackingHelper {
         typedef void Type;
     };
     template <typename Return, typename Metadata>
     static Return backingMalloc(size_t size)
     {
         return reinterpret_cast<Return>(partitionAllocGeneric(Partitions::getBufferPartition(), size));
     }
     template <typename Return, typename Metadata>
     static Return zeroedBackingMalloc(size_t size)
@@ skipping 63 matching lines @@
         ASSERT_NOT_REACHED();
         return false;
     }
 };
 
 } // namespace WTF
 
 using WTF::DefaultAllocator;
 
 #endif // WTF_DefaultAllocator_h