Added CSSPropertyCounterUtils which holds shared counter parsing logic.

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

Index: third_party/WebKit/Source/core/css/properties/CSSPropertyCounterUtils.h
diff --git a/third_party/WebKit/Source/core/css/properties/CSSPropertyCounterUtils.h b/third_party/WebKit/Source/core/css/properties/CSSPropertyCounterUtils.h
new file mode 100644
index 0000000000000000000000000000000000000000..57638b7864302e962f30b1745102b335c5432db2
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/properties/CSSPropertyCounterUtils.h
@@ -0,0 +1,25 @@
+// 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 CSSPropertyCounterUtils_h
+#define CSSPropertyCounterUtils_h
+
+#include "wtf/Allocator.h"
+
+namespace blink {
+
+class CSSParserTokenRange;
+class CSSValue;
+
+enum class CounterDefaultValue : int { kReset, kIncrement };
+
+class CSSPropertyCounterUtils {
+  STATIC_ONLY(CSSPropertyCounterUtils);
+
+  static CSSValue* consumeCounter(CSSParserTokenRange&, CounterDefaultValue);
+};
+
+}  // namespace blink
+
+#endif  // CSSPropertyCounterUtils_h