Web Animations CSS: Check if animating element exists before calculating animation update

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 1261 matching lines @@
             INCREMENT_STYLE_STATS_COUNTER(*this, matchedPropertyCacheInheritedHit);
 
             EInsideLink linkStatus = state.style()->insideLink();
             // If the cache item parent style has identical inherited properties to the current parent style then the
             // resulting style will be identical too. We copy the inherited properties over from the cache and are done.
             state.style()->inheritFrom(cachedMatchedProperties->renderStyle.get());
 
             // Unfortunately the link status is treated like an inherited property. We need to explicitly restore it.
             state.style()->setInsideLink(linkStatus);
 
-            if (RuntimeEnabledFeatures::webAnimationsCSSEnabled()
+            if (RuntimeEnabledFeatures::webAnimationsCSSEnabled() && animatingElement
                 && (animatingElement->hasActiveAnimations()
                     || (state.style()->transitions() && !state.style()->transitions()->isEmpty())
                     || (state.style()->animations() && !state.style()->animations()->isEmpty())))
                 applyAnimatedProperties(state, animatingElement);
             return;
         }
         applyInheritedOnly = true;
     }
 
     // First apply all variable definitions, as they may be used during application of later properties.
@@ skipping 132 matching lines @@
 bool StyleResolver::affectedByViewportChange() 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