Let unresolved custom element go through CustomElementCallbackQueue.

Source/core/dom/custom/CustomElement.cpp

Index: Source/core/dom/custom/CustomElement.cpp
diff --git a/Source/core/dom/custom/CustomElement.cpp b/Source/core/dom/custom/CustomElement.cpp
index 0dc1683ca39eb1d0e8fcddc8178b5413e162af22..27cdde94795e0876efbc0430334d8888317a4eb8 100644
--- a/Source/core/dom/custom/CustomElement.cpp
+++ b/Source/core/dom/custom/CustomElement.cpp
@@ -101,7 +101,9 @@ void CustomElement::define(Element* element, PassRefPtr<CustomElementDefinition>
 
     case Element::WaitingForUpgrade:
         definitions().add(element, definition);
-        CustomElementCallbackScheduler::scheduleCreatedCallback(definition->callbacks(), element);
+        if (element->inDocument() && element->document().domWindow())
+            CustomElementCallbackScheduler::scheduleAttachedCallback(definition->callbacks(), element);
+        definition->callbacks()->created(element);
         break;
     }
 }