Fix usage of pseudo style cache

Source/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 810 matching lines @@
     if (pseudoId < FIRST_INTERNAL_PSEUDOID && !parentRenderer->style()->hasPseudoStyle(pseudoId))
         return nullptr;
 
     if (pseudoId == BACKDROP && !parent.isInTopLayer())
         return nullptr;
 
     if (!parentRenderer->canHaveGeneratedChildren())
         return nullptr;
 
     RenderStyle* parentStyle = parentRenderer->style();
+    if (RenderStyle* cachedStyle = parentStyle->getCachedPseudoStyle(pseudoId)) {
+        if (!pseudoElementRendererIsNeeded(cachedStyle))
+            return nullptr;
+        return PseudoElement::create(&parent, pseudoId);
+    }
+
     StyleResolverState state(document(), &parent, parentStyle);
     if (!pseudoStyleForElementInternal(parent, pseudoId, parentStyle, state))
         return nullptr;
     RefPtr<RenderStyle> style = state.takeStyle();
     ASSERT(style);
+    parentStyle->addCachedPseudoStyle(style);
 
     if (!pseudoElementRendererIsNeeded(style.get()))
         return nullptr;
 
-    parentStyle->addCachedPseudoStyle(style.release());
     RefPtr<PseudoElement> pseudo = PseudoElement::create(&parent, pseudoId);
 
     setAnimationUpdateIfNeeded(state, *pseudo);
     if (ActiveAnimations* activeAnimations = pseudo->activeAnimations())
         activeAnimations->cssAnimations().maybeApplyPendingUpdate(pseudo.get());
     return pseudo.release();
 }
 
 bool StyleResolver::pseudoStyleForElementInternal(Element& element, const PseudoStyleRequest& pseudoStyleRequest, RenderStyle* parentStyle, StyleResolverState& state)
 {
@@ skipping 557 matching lines @@
 bool StyleResolver::mediaQueryAffectedByViewportChange() const
 {
     for (unsigned i = 0; i < m_viewportDependentMediaQueryResults.size(); ++i) {
         if (m_medium->eval(&m_viewportDependentMediaQueryResults[i]->m_expression) != m_viewportDependentMediaQueryResults[i]->m_result)
             return true;
     }
     return false;
 }
 
 } // namespace WebCore