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

Source/bindings/dart/custom/DartWebSocketCustom.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 26 matching lines @@
 
 namespace WebCore {
 
 namespace DartWebSocketInternal {
 
 void sendCallback(Dart_NativeArguments args)
 {
     Dart_Handle exception = 0;
     {
         WebSocket* receiver = DartDOMWrapper::receiver<WebSocket>(args);
-
-        DartDOMData* domData = static_cast<DartDOMData*>(Dart_GetNativeIsolateData(args));
         Dart_Handle dataHandle = Dart_GetNativeArgument(args, 1);
 
         DartExceptionState es;
         if (DartUtilities::isTypedData(dataHandle)) {
             RefPtr<ArrayBuffer> data = DartUtilities::dartToArrayBuffer(dataHandle, exception);
             if (exception)
                 goto fail;
             receiver->send(data.get(), es);
-        } else if (DartDOMWrapper::instanceOf<DartBlob>(domData, dataHandle)) {
+        } else if (DartDOMWrapper::subtypeOf(dataHandle, DartBlob::dartClassId)) {
             Blob* data = DartBlob::toNative(dataHandle, exception);
             if (exception)
                 goto fail;
             receiver->send(data, es);
         } else if (Dart_IsString(dataHandle)) {
             DartStringAdapter data = DartUtilities::dartToString(dataHandle, exception);
             if (exception)
                 goto fail;
             receiver->send(data, es);
         } else {
@@ skipping 113 matching lines @@
     }
 
 fail:
     Dart_ThrowException(exception);
     ASSERT_NOT_REACHED();
 }
 
 }
 
 }