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

Source/bindings/dart/DartCustomElementWrapper.cpp

Index: Source/bindings/dart/DartCustomElementWrapper.cpp
===================================================================
--- Source/bindings/dart/DartCustomElementWrapper.cpp	(revision 1437)
+++ Source/bindings/dart/DartCustomElementWrapper.cpp	(working copy)
@@ -114,13 +114,10 @@
 
     Dart_Handle newInstance = Dart_Allocate(customType);
     ASSERT(!Dart_IsError(newInstance));
+    DartDOMWrapper::writeNativePointer(newInstance, element, DartHTMLElement::dartClassId);
 
-    Dart_Handle result = Dart_SetNativeInstanceField(newInstance, 0, reinterpret_cast<intptr_t>(element));
-    UNUSED_PARAM(result);
-    ASSERT(!Dart_IsError(result));
+    Dart_Handle result = Dart_InvokeConstructor(newInstance, Dart_NewStringFromCString("created"), 0, 0);
 
-    result = Dart_InvokeConstructor(newInstance, Dart_NewStringFromCString("created"), 0, 0);
-
     if (Dart_IsError(result)) {
         DartUtilities::reportProblem(domData->scriptExecutionContext(), result);
 
@@ -136,10 +133,7 @@
         Dart_Handle fallbackWrapper = createUpgradeCandidateWrapper(element, createSpecificWrapper);
 
         DartDOMWrapper::associateWrapper<DartHTMLElement>(domData, element, fallbackWrapper);
-        Dart_Handle result = Dart_SetNativeInstanceField(fallbackWrapper, 0, reinterpret_cast<intptr_t>(element));
-        UNUSED_PARAM(result);
-        ASSERT(!Dart_IsError(result));
-
+        DartDOMWrapper::writeNativePointer(fallbackWrapper, element, DartHTMLElement::dartClassId);
         return fallbackWrapper;
     }
     return newInstance;