Remove fallback matching ::cue* pseudo-element selectors

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 2354 matching lines @@
 {
     if (ShadowRoot* root = containingShadowRoot()) {
         if (root->type() == ShadowRoot::UserAgentShadowRoot)
             return fastGetAttribute(pseudoAttr);
     }
     return nullAtom;
 }
 
 void Element::setShadowPseudoId(const AtomicString& id)
 {
-    ASSERT(CSSSelector::parsePseudoType(id, false) == CSSSelector::PseudoWebKitCustomElement || CSSSelector::parsePseudoType(id, false) == CSSSelector::PseudoUserAgentCustomElement);
+    ASSERT(CSSSelector::parsePseudoType(id, false) == CSSSelector::PseudoWebKitCustomElement);
     setAttribute(pseudoAttr, id);
 }
 
 bool Element::isInDescendantTreeOf(const Element* shadowHost) const
 {
     ASSERT(shadowHost);
     ASSERT(isShadowHost(shadowHost));
 
     const ShadowRoot* shadowRoot = containingShadowRoot();
     while (shadowRoot) {
@@ skipping 880 matching lines @@
         return wrapper;
 
     CustomElementBinding* binding = perContextData->customElementBinding(customElementDefinition());
 
     wrapper->SetPrototype(binding->prototype());
 
     return V8DOMWrapper::associateObjectWithWrapperNonTemplate(this, wrapperType, wrapper, isolate);
 }
 
 } // namespace blink