Simplify CustomElementScheduler by passing the enum for callback type directly.

Source/core/dom/custom/CustomElementCallbackInvocation.cpp

Index: Source/core/dom/custom/CustomElementCallbackInvocation.cpp
diff --git a/Source/core/dom/custom/CustomElementCallbackInvocation.cpp b/Source/core/dom/custom/CustomElementCallbackInvocation.cpp
index b7eb8e4d0d751e96b91eb0067b2efe6de5ec4e0a..a3afe31440b2ef1210f34ebe4fe27dfe1d2426c0 100644
--- a/Source/core/dom/custom/CustomElementCallbackInvocation.cpp
+++ b/Source/core/dom/custom/CustomElementCallbackInvocation.cpp
@@ -107,7 +107,7 @@ private:
 void CreatedInvocation::dispatch(Element* element)
 {
     if (element->inDocument() && element->document().domWindow())
-        CustomElementScheduler::scheduleAttachedCallback(callbacks(), element);
+        CustomElementScheduler::scheduleCallback(callbacks(), element, CustomElementLifecycleCallbacks::Attached);
     callbacks()->created(element);
 }