Don't mutate the DOM from inside an Element's constructor

Source/core/html/HTMLKeygenElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 14 matching lines @@
 #define HTMLKeygenElement_h
 
 #include "core/html/HTMLFormControlElementWithState.h"
 
 namespace WebCore {
 
 class HTMLSelectElement;
 
 class HTMLKeygenElement FINAL : public HTMLFormControlElementWithState {
 public:
-    static PassRefPtrWillBeRawPtr<HTMLKeygenElement> create(Document& document, HTMLFormElement* form)
-    {
-        return adoptRefWillBeRefCountedGarbageCollected(new HTMLKeygenElement(document, form));
-    }
+    static PassRefPtrWillBeRawPtr<HTMLKeygenElement> create(Document&, HTMLFormElement*);
 
     virtual bool willValidate() const OVERRIDE { return false; }
 
 private:
     HTMLKeygenElement(Document&, HTMLFormElement*);
 
     virtual bool areAuthorShadowsAllowed() const OVERRIDE { return false; }
 
     virtual bool canStartSelection() const OVERRIDE { return false; }
 
@@ skipping 12 matching lines @@
     virtual bool shouldSaveAndRestoreFormControlState() const OVERRIDE { return false; }
 
     virtual void didAddUserAgentShadowRoot(ShadowRoot&) OVERRIDE;
 
     HTMLSelectElement* shadowSelect() const;
 };
 
 } //namespace
 
 #endif