Update animation when changes in animation keyframes are detected.

Source/core/css/KeyframeStyleRuleCSSStyleDeclaration.cpp

Index: Source/core/css/KeyframeStyleRuleCSSStyleDeclaration.cpp
diff --git a/Source/core/css/KeyframeStyleRuleCSSStyleDeclaration.cpp b/Source/core/css/KeyframeStyleRuleCSSStyleDeclaration.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..fe9414274e7f13bf8d6c92c6fa3c00eb6356f909
--- /dev/null
+++ b/Source/core/css/KeyframeStyleRuleCSSStyleDeclaration.cpp
@@ -0,0 +1,23 @@
+// Copyright 2015 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 "config.h"
+#include "core/css/KeyframeStyleRuleCSSStyleDeclaration.h"
+
+#include "core/css/CSSKeyframesRule.h"
+
+namespace blink {
+
+KeyframeStyleRuleCSSStyleDeclaration::KeyframeStyleRuleCSSStyleDeclaration(MutableStylePropertySet& propertySetArg, CSSKeyframeRule* parentRule)
+    : StyleRuleCSSStyleDeclaration(propertySetArg, parentRule)
+{
+}
+
+void KeyframeStyleRuleCSSStyleDeclaration::didMutate(MutationType type)
+{
+    StyleRuleCSSStyleDeclaration::didMutate(type);
+    toCSSKeyframesRule(m_parentRule->parentRule())->styleChanged();
+}
+
+} // namespace blink