DOM wrappers that are not retained from Dart should be collected.

Source/WebCore/bindings/dart/DartDOMWrapper.cpp

 // Copyright 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:
 //
 //    * 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 58 matching lines @@
 #include "DartXMLHttpRequestException.h"
 #include "XPathException.h"
 #include "DartXPathException.h"
 // end of FIXME
 
 #include <stdio.h>
 #include <wtf/text/WTFString.h>
 
 namespace WebCore {
 
-void DartDOMWrapper::derefDOMObject(Dart_Handle wrapper, void* domObject)
-{
-    ASSERT(domObject == readNativePointer(wrapper, kNativeImplementationIndex));
-    DerefObjectFunction derefObjectFunction = reinterpret_cast<DerefObjectFunction>(readNativePointer(wrapper, kDerefObjectFunctionIndex));
-    (*derefObjectFunction)(domObject);
-}
-
 Dart_Handle DartDOMWrapper::instantiateWrapper(const char* className)
 {
     // FIXME: this all is very ugly, but we're blocked by API here.
     // In this case we need an API to invoke ctor, or even better,
     // create an instance without exposing constructor at all.
     String factoryMethodName = String("_create") + className;
     Dart_Handle dom = Dart_LookupLibrary(Dart_NewString(DartUtilities::domLibraryName));
     ASSERT(!Dart_IsError(dom));
 
     Dart_Handle instance = Dart_InvokeStatic(dom, Dart_NewString(className), DartUtilities::stringToDartString(factoryMethodName), 0, 0);
@@ skipping 54 matching lines @@
     return toDartValue(static_cast<HTMLElement*>(value));
 }
 
 Dart_Handle toDartValue(NPObject* object)
 {
     // FIXME: put NPObjects into a map as well.
     return DartDOMWrapper::newWrapper("NPObject", object);
 }
 
 }