WIP (Introduce WTF::NonNullPtr<T>.)

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 82 matching lines @@
     m_result.ranges.lastAuthorRule = m_result.matchedProperties.size();
     if (m_result.ranges.firstAuthorRule == -1)
         m_result.ranges.firstAuthorRule = m_result.ranges.lastAuthorRule;
     m_result.addMatchedProperties(propertySet);
     if (!isCacheable)
         m_result.isCacheable = false;
 }
 
 static bool rulesApplicableInCurrentTreeScope(const Element* element, const ContainerNode* scopingNode, SelectorChecker::BehaviorAtBoundary behaviorAtBoundary, bool elementApplyAuthorStyles)
 {
-    TreeScope& treeScope = element->treeScope();
+    NonNullPtr<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())
+    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())
         return true;
     // e) the rules can cross boundaries
     if ((behaviorAtBoundary & SelectorChecker::BoundaryBehaviorMask) == SelectorChecker::CrossesBoundary)
         return true;
     return false;
 }
 
@@ skipping 196 matching lines @@
     m_behaviorAtBoundary = SelectorChecker::StaysWithinTreeScope;
     int firstRuleIndex = -1, lastRuleIndex = -1;
     RuleRange ruleRange(firstRuleIndex, lastRuleIndex);
     // FIXME: Verify whether it's ok to ignore CascadeScope here.
     collectMatchingRules(MatchRequest(ruleSet), ruleRange);
 
     return m_matchedRules && !m_matchedRules->isEmpty();
 }
 
 } // namespace WebCore