Change shadow style's scope from Shadow Host to Shadow Root

Source/core/css/ElementRuleCollector.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 112 matching lines @@
     TreeScope& treeScope = element->treeScope();
 
     // [skipped, because already checked] a) it's a UA rule
     // b) element is allowed to apply author rules
     if (elementApplyAuthorStyles)
         return true;
     // c) the rules comes from a scoped style sheet within the same tree scope
     if (!scopingNode || treeScope == scopingNode->treeScope())
         return true;
     // d) the rules comes from a scoped style sheet within an active shadow root whose host is the given element
-    if (element->isInShadowTree() && (behaviorAtBoundary & SelectorChecker::ScopeIsShadowHost) && scopingNode == element->containingShadowRoot()->host())
+    if (SelectorChecker::isHostInItsShadowTree(*element, behaviorAtBoundary, scopingNode))
         return true;
     return false;
 }
 
 void ElementRuleCollector::collectMatchingRules(const MatchRequest& matchRequest, RuleRange& ruleRange, SelectorChecker::BehaviorAtBoundary behaviorAtBoundary, CascadeScope cascadeScope, CascadeOrder cascadeOrder)
 {
     ASSERT(matchRequest.ruleSet);
     ASSERT(m_context.element());
 
     Element& element = *m_context.element();
@@ skipping 198 matching lines @@
     // information about "scope".
     int firstRuleIndex = -1, lastRuleIndex = -1;
     RuleRange ruleRange(firstRuleIndex, lastRuleIndex);
     // FIXME: Verify whether it's ok to ignore CascadeScope here.
     collectMatchingRules(MatchRequest(ruleSet), ruleRange, SelectorChecker::StaysWithinTreeScope);
 
     return m_matchedRules && !m_matchedRules->isEmpty();
 }
 
 } // namespace WebCore