Update animation when changes in animation keyframes are detected.

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 997 matching lines @@
     applyAnimatedProperties<LowPriorityProperties>(state, activeInterpolationsForTransitions);
 
     // Start loading resources used by animations.
     loadPendingResources(state);
 
     ASSERT(!state.fontBuilder().fontDirty());
 
     return true;
 }
 
-const StyleRuleKeyframes* StyleResolver::findKeyframesRule(const Element* element, const AtomicString& animationName)
+StyleRuleKeyframes* StyleResolver::findKeyframesRule(const Element* element, const AtomicString& animationName)
 {
     WillBeHeapVector<RawPtrWillBeMember<ScopedStyleResolver>, 8> resolvers;
     collectScopedResolversForHostedShadowTrees(element, resolvers);
     if (ScopedStyleResolver* scopedResolver = element->treeScope().scopedStyleResolver())
         resolvers.append(scopedResolver);
 
     for (size_t i = 0; i < resolvers.size(); ++i) {
-        if (const StyleRuleKeyframes* keyframesRule = resolvers[i]->keyframeStylesForAnimation(animationName.impl()))
+        if (StyleRuleKeyframes* keyframesRule = resolvers[i]->keyframeStylesForAnimation(animationName.impl()))
             return keyframesRule;
     }
     return nullptr;
 }
 
 template <StyleResolver::StyleApplicationPass pass>
 void StyleResolver::applyAnimatedProperties(StyleResolverState& state, const WillBeHeapHashMap<CSSPropertyID, RefPtrWillBeMember<Interpolation> >& activeInterpolations)
 {
     for (const auto& interpolationEntry : activeInterpolations) {
         CSSPropertyID property = interpolationEntry.key;
@@ skipping 536 matching lines @@
     visitor->trace(m_uncommonAttributeRuleSet);
     visitor->trace(m_watchedSelectorsRules);
     visitor->trace(m_treeBoundaryCrossingRules);
     visitor->trace(m_styleSharingLists);
     visitor->trace(m_pendingStyleSheets);
     visitor->trace(m_document);
 #endif
 }
 
 } // namespace blink