Prepare for responsive CSS animations.

Source/core/animation/StringKeyframe.cpp

Index: Source/core/animation/StringKeyframe.cpp
diff --git a/Source/core/animation/StringKeyframe.cpp b/Source/core/animation/StringKeyframe.cpp
index 90b68cb8b2e85261872802d33c35f5fb5f89f01a..50a98f25f0e0399f31de7c1f38b42c6a4d06d856 100644
--- a/Source/core/animation/StringKeyframe.cpp
+++ b/Source/core/animation/StringKeyframe.cpp
@@ -6,6 +6,7 @@
 #include "core/animation/StringKeyframe.h"
 
 #include "core/animation/ColorStyleInterpolation.h"
+#include "core/animation/CompositorAnimations.h"
 #include "core/animation/ConstantStyleInterpolation.h"
 #include "core/animation/DefaultStyleInterpolation.h"
 #include "core/animation/DeferredLegacyStyleInterpolation.h"
@@ -17,6 +18,7 @@
 #include "core/animation/LengthPoint3DStyleInterpolation.h"
 #include "core/animation/LengthStyleInterpolation.h"
 #include "core/animation/VisibilityStyleInterpolation.h"
+#include "core/animation/css/CSSAnimatableValueFactory.h"
 #include "core/animation/css/CSSAnimations.h"
 #include "core/css/CSSPropertyMetadata.h"
 #include "core/css/resolver/StyleResolver.h"
@@ -37,6 +39,13 @@ void StringKeyframe::setPropertyValue(CSSPropertyID property, const String& valu
         m_propertySet->setProperty(property, value, false, styleSheetContents);
 }
 
+void StringKeyframe::setPropertyValue(CSSPropertyID property, PassRefPtr<CSSValue> value)
+{
+    ASSERT(property != CSSPropertyInvalid);
+    if (CSSAnimations::isAllowedAnimation(property))
+        m_propertySet->setProperty(property, value, false);
+}
+
 PropertySet StringKeyframe::properties() const
 {
     // This is not used in time-critical code, so we probably don't need to
@@ -74,6 +83,11 @@ StringKeyframe::PropertySpecificKeyframe::PropertySpecificKeyframe(double offset
     ASSERT(!isNull(m_offset));
 }
 
+void StringKeyframe::PropertySpecificKeyframe::setAnimatableValue(PassRefPtr<AnimatableValue> value)
+{
+    m_animatableValueCache = value;
+}
+
 // FIXME: Refactor this into a generic piece that lives in InterpolationEffect, and a template parameter specific converter.
 PassRefPtrWillBeRawPtr<Interpolation> StringKeyframe::PropertySpecificKeyframe::maybeCreateInterpolation(CSSPropertyID property, Keyframe::PropertySpecificKeyframe& end, Element* element) const
 {
@@ -82,6 +96,12 @@ PassRefPtrWillBeRawPtr<Interpolation> StringKeyframe::PropertySpecificKeyframe::
     InterpolationRange range = RangeAll;
     bool fallBackToLegacy = false;
 
+    // FIXME: Remove this check once neutral keyframes are implemented in StringKeyframes.
+    if (!fromCSSValue || !toCSSValue)
+        return DeferredLegacyStyleInterpolation::create(fromCSSValue, toCSSValue, property);
+
+    ASSERT(fromCSSValue && toCSSValue);
+
     if (!CSSPropertyMetadata::isAnimatableProperty(property)) {
         // FIXME: Remove this once TimingFunction partitioning is implemented for all types.
         if (!RuntimeEnabledFeatures::webAnimationsAPITimingFunctionPartitioningEnabled())