Support interpolation of animatable shorthand properties containing var()

third_party/WebKit/Source/core/animation/StringKeyframe.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/animation/StringKeyframe.h"
 
 #include "core/StylePropertyShorthand.h"
 #include "core/animation/css/CSSAnimations.h"
 #include "core/css/CSSPropertyMetadata.h"
 #include "core/css/resolver/StyleResolver.h"
@@ skipping 37 matching lines @@
     m_svgAttributeMap.set(&attributeName, value);
 }
 
 PropertyHandleSet StringKeyframe::properties() const
 {
     // This is not used in time-critical code, so we probably don't need to
     // worry about caching this result.
     PropertyHandleSet properties;
     for (unsigned i = 0; i < m_cssPropertyMap->propertyCount(); ++i) {
         StylePropertySet::PropertyReference propertyReference = m_cssPropertyMap->propertyAt(i);
-        DCHECK(
-            !isShorthandProperty(propertyReference.id()) || propertyReference.value().isVariableReferenceValue())
+        DCHECK(!isShorthandProperty(propertyReference.id()))
             << "Web Animations: Encountered unexpanded shorthand CSS property (" << propertyReference.id() << ").";
         properties.add(PropertyHandle(propertyReference.id(), false));
     }
 
     for (unsigned i = 0; i < m_presentationAttributeMap->propertyCount(); ++i)
         properties.add(PropertyHandle(m_presentationAttributeMap->propertyAt(i).id(), true));
 
     for (const auto& key: m_svgAttributeMap.keys())
         properties.add(PropertyHandle(*key));
 
@@ skipping 39 matching lines @@
 {
     return create(offset, m_easing, m_value, m_composite);
 }
 
 PassRefPtr<Keyframe::PropertySpecificKeyframe> SVGPropertySpecificKeyframe::neutralKeyframe(double offset, PassRefPtr<TimingFunction> easing) const
 {
     return create(offset, std::move(easing), String(), EffectModel::CompositeAdd);
 }
 
 } // namespace blink