Fixed some memory leaks in unit tests.

test/cctest/test-ast.cc

 // Copyright 2006-2008 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 35 matching lines @@
   CHECK_EQ(node, list->last());
 
   const int kElements = 100;
   for (int i = 0; i < kElements; i++) {
     list->Add(node);
   }
   CHECK_EQ(1 + kElements, list->length());
 
   list->Clear();
   CHECK_EQ(0, list->length());
+  delete list;
 }
 
 
 TEST(RemoveLast) {
   List<int> list(4);
   CHECK_EQ(0, list.length());
   list.Add(1);
   CHECK_EQ(1, list.length());
   CHECK_EQ(1, list.last());
   list.RemoveLast();
@@ skipping 21 matching lines @@
 
 TEST(DeleteEmpty) {
   {
     List<int>* list = new List<int>(0);
     delete list;
   }
   {
     List<int> list(0);
   }
 }