Get rid of the overloads on templated traversal methods for clarity and safety

Source/wtf/TreeNodeTest.cpp

 /*
  * Copyright (C) 2012 Apple 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 177 matching lines @@
 {
     TrioWithGrandChild trio;
     trio.appendChildren();
 
     TestTree* order[] = {
         trio.root.get(), trio.firstChild.get(), trio.middleChild.get(),
         trio.grandChild.get(), trio.lastChild.get()
     };
 
     unsigned orderIndex = 0;
-    for (TestTree* node = trio.root.get(); node; node = traverseNext(*node), orderIndex++)
+    for (TestTree* node = trio.root.get(); node; node = traverseNext<TestTree>(*node), orderIndex++)
         ASSERT_EQ(node, order[orderIndex]);
     ASSERT_EQ(orderIndex, sizeof(order) / sizeof(TestTree*));
 }
 
 TEST(WTF, TreeNodeTraverseNextPostORder)
 {
     TrioWithGrandChild trio;
     trio.appendChildren();
 
 
     TestTree* order[] = {
         trio.firstChild.get(),
         trio.grandChild.get(), trio.middleChild.get(), trio.lastChild.get(), trio.root.get()
     };
 
     unsigned orderIndex = 0;
-    for (TestTree* node = traverseFirstPostOrder(*trio.root.get()); node; node = traverseNextPostOrder(*node), orderIndex++)
+    for (TestTree* node = traverseFirstPostOrder<TestTree>(*trio.root.get()); node; node = traverseNextPostOrder<TestTree>(*node), orderIndex++)
         ASSERT_EQ(node, order[orderIndex]);
     ASSERT_EQ(orderIndex, sizeof(order) / sizeof(TestTree*));
 
 }
 
 
 } // namespace