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

Source/bindings/dart/DartUtilities.cpp

Index: Source/bindings/dart/DartUtilities.cpp
===================================================================
--- Source/bindings/dart/DartUtilities.cpp	(revision 1437)
+++ Source/bindings/dart/DartUtilities.cpp	(working copy)
@@ -339,12 +339,6 @@
     return dartToDate(object, exception);
 }
 
-bool DartUtilities::isHtmlElement(DartDOMData* domData, Dart_Handle handle)
-{
-    ASSERT(domData);
-    return DartDOMWrapper::instanceOf<DartHTMLElement>(domData, handle);
-}
-
 bool DartUtilities::isDateTime(DartDOMData* domData, Dart_Handle handle)
 {
     ASSERT(domData);