Revert of Remove scoped styles.

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 3268 matching lines @@
     // Ids stop style sharing if they show up in the stylesheets.
     if (hasID() && document().ensureStyleResolver().hasRulesForId(idForStyleResolution()))
         return false;
     // :active and :hover elements always make a chain towards the document node
     // and no siblings or cousins will have the same state. There's also only one
     // :focus element per scope so we don't need to attempt to share.
     if (isUserActionElement())
         return false;
     if (!parentOrShadowHostElement()->childrenSupportStyleSharing())
         return false;
+    if (hasScopedHTMLStyleChild())
+        return false;
     if (this == document().cssTarget())
         return false;
     if (isHTMLElement() && toHTMLElement(this)->hasDirectionAuto())
         return false;
     if (hasActiveAnimations())
         return false;
     // Turn off style sharing for elements that can gain layers for reasons outside of the style system.
     // See comments in RenderObject::setStyle().
     // FIXME: Why does gaining a layer from outside the style system require disabling sharing?
     if (isHTMLFrameElementBase(*this)
         || isHTMLEmbedElement(*this)
         || isHTMLObjectElement(*this)
         || isHTMLAppletElement(*this)
         || isHTMLCanvasElement(*this))
         return false;
     if (FullscreenElementStack::isActiveFullScreenElement(this))
         return false;
     return true;
 }
 
 void Element::trace(Visitor* visitor)
 {
     if (hasRareData())
         visitor->trace(elementRareData());
 
     ContainerNode::trace(visitor);
 }
 
 } // namespace WebCore