Process Custom Elements in post-order.

Source/core/dom/CustomElementRegistrationContext.h

Index: Source/core/dom/CustomElementRegistrationContext.h
diff --git a/Source/core/dom/CustomElementRegistrationContext.h b/Source/core/dom/CustomElementRegistrationContext.h
index 64099d398594c316fdb4d1266dd7698c7caa5c40..1c3336ed35fcd44511ae32b59bec24958b6f06c8 100644
--- a/Source/core/dom/CustomElementRegistrationContext.h
+++ b/Source/core/dom/CustomElementRegistrationContext.h
@@ -57,12 +57,14 @@ public:
     void registerElement(Document*, CustomElementConstructorBuilder*, const AtomicString& type, ExceptionState&);
 
     // Instance creation
-    PassRefPtr<Element> createCustomTagElement(Document*, const QualifiedName&);
-    static void setIsAttributeAndTypeExtension(Element*, const AtomicString& type);
-    static void setTypeExtension(Element*, const AtomicString& type);
+    enum CreationMode {
+        CreatedByParser,
+        NotCreatedByParser
+    };
 
-    // Instance lifecycle
-    void customElementWasDestroyed(Element*);
+    PassRefPtr<Element> createCustomTagElement(Document*, const QualifiedName&, CreationMode = NotCreatedByParser);
+    static void setIsAttributeAndTypeExtension(Element*, const AtomicString& type);
+    static void setTypeExtension(Element*, const AtomicString& type, CreationMode = NotCreatedByParser);
 
 protected:
     CustomElementRegistrationContext() { }