Add a native subtype of function that uses the native C++ class hierarchy to check if an element

Source/bindings/dart/DartNativeUtilities.cpp

 // Copyright 2012, 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 176 matching lines @@
 fail:
     Dart_ThrowException(exception);
     ASSERT_NOT_REACHED();
 }
 
 void initializeCustomElement(Dart_NativeArguments args)
 {
     Dart_Handle exception = 0;
     {
         Dart_Handle elementWrapper = Dart_GetNativeArgument(args, 0);
-        DartDOMData* domData = static_cast<DartDOMData*>(Dart_GetNativeIsolateData(args));
-        if (!DartUtilities::isHtmlElement(domData, elementWrapper)) {
+        if (!DartDOMWrapper::subtypeOf(elementWrapper, DartHTMLElement::dartClassId)) {
             exception = Dart_NewStringFromCString("Invalid class: expected instance of HtmlElement");
             goto fail;
         }
         DartCustomElementWrapper<HTMLElement>::initializeCustomElement(elementWrapper, exception);
         if (exception) {
             goto fail;
         }
         return;
     }
 
@@ skipping 36 matching lines @@
     if (argumentCount == 1 && str == "Utils_initializeCustomElement")
         return DartNativeUtilitiesInternal::initializeCustomElement;
     if (argumentCount == 1 && str == "Window_history_cross_frame_Getter")
         return DartWindowInternal::historyCrossFrameGetter;
     if (argumentCount == 1 && str == "Window_location_cross_frame_Getter")
         return DartWindowInternal::locationCrossFrameGetter;
     return 0;
 }
 
 }