Add a comma delimited syntax parser and use it for Accept-CH

Source/platform/CommaDelimitedParser.cpp

+// 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 "platform/CommaDelimitedParser.h"
+
+namespace blink {
+
+static bool isWhitespace(UChar chr)
+{
+    return (chr == ' ') || (chr == '\t');
+}
+
+CommaDelimitedParser::CommaDelimitedParser(String input)
+{
+    Vector<String> results;
+    input.split(",", results);
+    for (auto& value : results)
+        m_map.add(value.stripWhiteSpace(isWhitespace), true);
+}
+
+bool CommaDelimitedParser::contains(String field)
+{
+    auto i = m_map.find(field);
+    if (i == m_map.end())
+        return false;
+    return i->value;
+}
+
+} // namespace blink
+