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 f4bba26b2017d6e227e38baba5c416dd12336039..2911dc5ccf0d103b6f9e1024bb6dc02fef57f613 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/DeferredLegacyStyleInterpolation.h"
 #include "core/animation/DoubleStyleInterpolation.h"
@@ -38,6 +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);
+    ASSERT(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
@@ -75,6 +83,11 @@ StringKeyframe::PropertySpecificKeyframe::PropertySpecificKeyframe(double offset
     ASSERT(!isNull(m_offset));
 }
 
+void StringKeyframe::PropertySpecificKeyframe::setAnimatableValue(PassRefPtr<AnimatableValue> value)
+{
+    m_animatableValueCache = value;
+}
+
 namespace {
 InterpolationRange setRange(CSSPropertyID id)
 {
@@ -117,6 +130,12 @@ PassRefPtrWillBeRawPtr<Interpolation> StringKeyframe::PropertySpecificKeyframe::
     // FIXME: Remove this flag once we can rely on legacy's behaviour being correct.
     bool forceDefaultInterpolation = 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)) {
         if (fromCSSValue == toCSSValue)
             return ConstantStyleInterpolation::create(fromCSSValue, property);