Only allow one shadowRoot.

sky/engine/core/css/resolver/StyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 664 matching lines @@
         resolvers.append(scopedResolver);
 }
 
 void StyleResolver::collectScopedResolversForHostedShadowTrees(const Element* element, Vector<RawPtr<ScopedStyleResolver>, 8>& resolvers)
 {
     ElementShadow* shadow = element->shadow();
     if (!shadow)
         return;
 
     // Adding scoped resolver for active shadow roots for shadow host styling.
-    for (ShadowRoot* shadowRoot = shadow->youngestShadowRoot(); shadowRoot; shadowRoot = shadowRoot->olderShadowRoot()) {
+    if (ShadowRoot* shadowRoot = shadow->shadowRoot()) {
         if (shadowRoot->numberOfStyles() > 0) {
             if (ScopedStyleResolver* resolver = shadowRoot->scopedStyleResolver())
                 resolvers.append(resolver);
         }
     }
 }
 
 void StyleResolver::styleTreeResolveScopedKeyframesRules(const Element* element, Vector<RawPtr<ScopedStyleResolver>, 8>& resolvers)
 {
     Document& document = element->document();
@@ skipping 299 matching lines @@
 bool StyleResolver::mediaQueryAffectedByViewportChange() const
 {
     for (unsigned i = 0; i < m_viewportDependentMediaQueryResults.size(); ++i) {
         if (m_medium->eval(m_viewportDependentMediaQueryResults[i]->expression()) != m_viewportDependentMediaQueryResults[i]->result())
             return true;
     }
     return false;
 }
 
 } // namespace blink