UA shadow root of <marquee> should not be exposed to user scripts

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1653 matching lines @@
     // as children so we can't allow author shadows on them for now. An override
     // flag is provided for testing how author shadows interact on these elements.
     if (!areAuthorShadowsAllowed() && !RuntimeEnabledFeatures::authorShadowDOMForAnyElementEnabled()) {
         exceptionState.throwDOMException(HierarchyRequestError, "Author-created shadow roots are disabled for this element.");
         return nullptr;
     }
 
     return PassRefPtrWillBeRawPtr<ShadowRoot>(ensureShadow().addShadowRoot(*this, ShadowRoot::AuthorShadowRoot));
 }
 
+PassRefPtrWillBeRawPtr<ShadowRoot> Element::createUserAgentShadowRoot(ExceptionState& exceptionState)
+{
+    return PassRefPtrWillBeRawPtr<ShadowRoot>(ensureUserAgentShadowRoot());
+}
+
 ShadowRoot* Element::shadowRoot() const
 {
     ElementShadow* elementShadow = shadow();
     if (!elementShadow)
         return 0;
     ShadowRoot* shadowRoot = elementShadow->youngestShadowRoot();
     if (shadowRoot->type() == ShadowRoot::AuthorShadowRoot)
         return shadowRoot;
     return 0;
 }
@@ skipping 1580 matching lines @@
         return wrapper;
 
     CustomElementBinding* binding = perContextData->customElementBinding(customElementDefinition());
 
     wrapper->SetPrototype(binding->prototype());
 
     return V8DOMWrapper::associateObjectWithWrapperNonTemplate(this, wrapperType, wrapper, isolate);
 }
 
 } // namespace blink