Oilpan: move ClientRect and its list to the oilpan heap.

Source/core/dom/ClientRectList.cpp

 /*
  * Copyright (C) 2009 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 46 matching lines @@
 {
     if (index >= m_list.size()) {
         // FIXME: this should throw an exception.
         // ec = IndexSizeError;
         return 0;
     }
 
     return m_list[index].get();
 }
 
+void ClientRectList::trace(Visitor *visitor)
+{
+    visitor->trace(m_list);
+}
+
 } // namespace WebCore