Set a bit on Custom Elements on creation to simplify wrapping

Source/bindings/v8/CustomElementHelpers.h

Index: Source/bindings/v8/CustomElementHelpers.h
diff --git a/Source/bindings/v8/CustomElementHelpers.h b/Source/bindings/v8/CustomElementHelpers.h
index 67e779fd140baca63cf438bad5e0aed1d797bfb7..93020af35a991f2367f154ffe67dfc9a2dc0a1ba 100644
--- a/Source/bindings/v8/CustomElementHelpers.h
+++ b/Source/bindings/v8/CustomElementHelpers.h
@@ -88,8 +88,6 @@ public:
     // proper prototype instances accordingly.
     static v8::Handle<v8::Object> wrap(Element*, v8::Handle<v8::Object> creationContext, v8::Isolate*, const CreateWrapperFunction& createTypeExtensionUpgradeCandidateWrapper);
 
-    static bool isCustomElement(Element*);
-
 private:
     static void invokeReadyCallbackIfNeeded(Element*, v8::Handle<v8::Context>);
     static v8::Handle<v8::Object> createWrapper(PassRefPtr<Element>, v8::Handle<v8::Object>, v8::Isolate*, const CreateWrapperFunction& createTypeExtensionUpgradeCandidateWrapper);