Web Animations CSS: Assert underlying value is not used

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 1144 matching lines @@
 
     for (size_t i = 0; i < animations.size(); ++i) {
         RefPtr<Animation> animation = animations.at(i);
         if (update && update->isFiltered(animation->player()))
             continue;
         const AnimationEffect::CompositableValueMap* compositableValues = animation->compositableValues();
         for (AnimationEffect::CompositableValueMap::const_iterator iter = compositableValues->begin(); iter != compositableValues->end(); ++iter) {
             CSSPropertyID property = iter->key;
             if (!isPropertyForPass<pass>(property))
                 continue;
-            RefPtr<AnimatableValue> animatableValue = iter->value->compositeOnto(AnimatableValue::neutralValue());
+            RELEASE_ASSERT_WITH_MESSAGE(!iter->value->dependsOnUnderlyingValue(), "Not yet implemented: An interface for compositing onto the underlying value.");
+            RefPtr<AnimatableValue> animatableValue = iter->value->compositeOnto(0);
             if (pass == HighPriorityProperties && property == CSSPropertyLineHeight)
                 state.setLineHeightValue(toAnimatableNumber(animatableValue.get())->toCSSValue().get());
             else
                 AnimatedStyleBuilder::applyProperty(property, state, animatableValue.get());
         }
     }
 }
 
 // http://dev.w3.org/csswg/css3-regions/#the-at-region-style-rule
 // FIXME: add incremental support for other region styling properties.
@@ skipping 350 matching lines @@
         m_matchedPropertiesSearches, m_matchedPropertiesHit, m_matchedPropertiesSharedInheritedHit, m_matchedPropertiesToCache, m_matchedPropertiesEnteredIntoCache);
 
     fprintf(stderr, "Total:\n");
     printStyleStats(m_totalSearches, m_totalElementsEligibleForSharing, m_totalStylesShared, m_totalSearchFoundSiblingForSharing, m_totalSearchesMissedSharing,
         m_totalMatchedPropertiesSearches, m_totalMatchedPropertiesHit, m_totalMatchedPropertiesSharedInheritedHit, m_totalMatchedPropertiesToCache, m_totalMatchedPropertiesEnteredIntoCache);
     fprintf(stderr, "--------------------------------------------------------------------------------\n");
 }
 #endif
 
 } // namespace WebCore