Update the snap points css properties

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIScrollSnapType.cpp

+// 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.
+
+#include "core/css/properties/CSSPropertyAPIScrollSnapType.h"
+
+#include "core/css/CSSValuePair.h"
+#include "core/css/parser/CSSPropertyParserHelpers.h"
+
+namespace blink {
+
+const CSSValue* CSSPropertyAPIScrollSnapType::parseSingleValue(
+    CSSParserTokenRange& range,
+    const CSSParserContext& context,
+    const CSSParserLocalContext&) {
+  CSSValueID axis_id = range.Peek().Id();
+  if (axis_id != CSSValueNone && axis_id != CSSValueX && axis_id != CSSValueY &&
+      axis_id != CSSValueBlock && axis_id != CSSValueInline &&
+      axis_id != CSSValueBoth)
+    return nullptr;
+  CSSValue* axis_value = CSSPropertyParserHelpers::ConsumeIdent(range);
+  if (range.AtEnd() || axis_id == CSSValueNone)
+    return axis_value;
+
+  CSSValueID strictness_id = range.Peek().Id();
+  if (strictness_id != CSSValueProximity && strictness_id != CSSValueMandatory)
+    return axis_value;
+  CSSValue* strictness_value = CSSPropertyParserHelpers::ConsumeIdent(range);
+  CSSValuePair* pair = CSSValuePair::Create(axis_value, strictness_value,
+                                            CSSValuePair::kDropIdenticalValues);
+  return pair;
+}
+
+}  // namespace blink