Destruct all instances of value types in WTF::HashTable.

Source/wtf/HashMapTest.cpp

 /*
  * Copyright (C) 2011 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 266 matching lines @@
     EXPECT_EQ(11, map.find(1)->value.first());
 
     IntVectorMap::AddResult result2 = map.add(1, Vector<int>());
     EXPECT_FALSE(result2.isNewEntry);
     EXPECT_EQ(1, result.storedValue->key);
     EXPECT_EQ(1u, result.storedValue->value.size());
     EXPECT_EQ(11, result.storedValue->value.first());
     EXPECT_EQ(11, map.find(1)->value.first());
 }
 
+class InstanceCounter {
+public:
+    InstanceCounter() { ++counter; }
+    InstanceCounter(const InstanceCounter& another) { ++counter; }
+    ~InstanceCounter() { --counter; }
+    static int counter;
+};
+int InstanceCounter::counter = 0;
+
+TEST(HashMapTest, ValueTypeDestructed)
+{
+    InstanceCounter::counter = 0;
+    HashMap<int, InstanceCounter> map;
+    map.set(1, InstanceCounter());
+    map.clear();
+    EXPECT_EQ(0, InstanceCounter::counter);
+}
+
 } // namespace