Added CSSPropertyTransitionPropertyUtils which holds shared parsing logic.

third_party/WebKit/Source/core/css/properties/CSSPropertyTransitionPropertyUtils.h

Index: third_party/WebKit/Source/core/css/properties/CSSPropertyTransitionPropertyUtils.h
diff --git a/third_party/WebKit/Source/core/css/properties/CSSPropertyTransitionPropertyUtils.h b/third_party/WebKit/Source/core/css/properties/CSSPropertyTransitionPropertyUtils.h
new file mode 100644
index 0000000000000000000000000000000000000000..b06605a188ce1f3b298aba111073f4d8128769c5
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/properties/CSSPropertyTransitionPropertyUtils.h
@@ -0,0 +1,26 @@
+// Copyright 2017 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.
+
+#ifndef CSSPropertyTransitionPropertyUtils_h
+#define CSSPropertyTransitionPropertyUtils_h
+
+#include "platform/wtf/Allocator.h"
+
+namespace blink {
+
+class CSSParserTokenRange;
+class CSSValue;
+class CSSValueList;
+
+class CSSPropertyTransitionPropertyUtils {
+  STATIC_ONLY(CSSPropertyTransitionPropertyUtils);
+
+ public:
+  static CSSValue* ConsumeTransitionProperty(CSSParserTokenRange&);
+  static bool IsValidPropertyList(const CSSValueList&);
+};
+
+}  // namespace blink
+
+#endif  // CSSPropertyTransitionPropertyUtils_h