Revert 149589 "Set a bit on Custom Elements on creation to simplify wrapping"

Source/bindings/v8/CustomElementHelpers.cpp

Index: Source/bindings/v8/CustomElementHelpers.cpp
diff --git a/Source/bindings/v8/CustomElementHelpers.cpp b/Source/bindings/v8/CustomElementHelpers.cpp
index 674f4e97ef0ce62aca5b954088a12a4631b3fdf3..044ec595d8a614f4a66780dcc7086c3f1902651e 100644
--- a/Source/bindings/v8/CustomElementHelpers.cpp
+++ b/Source/bindings/v8/CustomElementHelpers.cpp
@@ -242,6 +242,13 @@ const QualifiedName* CustomElementHelpers::findLocalName(v8::Handle<v8::Object>
     return 0;
 }
 
+bool CustomElementHelpers::isCustomElement(Element* element)
+{
+    // FIXME: This dynamically consults the "is" attribute; instead a
+    // bit should be marked on elements that are Custom Elements
+    return CustomElementRegistry::isCustomTagName(element->localName()) || CustomElementRegistry::isCustomTagName(element->getAttribute(HTMLNames::isAttr));
+}
+
 void CustomElementHelpers::invokeReadyCallbackIfNeeded(Element* element, v8::Handle<v8::Context> context)
 {
     v8::Handle<v8::Value> wrapperValue = toV8(element, context->Global(), context->GetIsolate());