Implemented the CSSPropertyAPI for the font-family property.

third_party/WebKit/Source/core/css/properties/CSSPropertyAPIFontFamily.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/CSSPropertyAPIFontFamily.h"
+
+#include "core/css/CSSValueList.h"
+#include "core/css/properties/CSSPropertyFontUtils.h"
+
+class CSSParserContext;
+
+namespace blink {
+
+const CSSValue* CSSPropertyAPIFontFamily::parseSingleValue(
+    CSSParserTokenRange& range,
+    const CSSParserContext*) {
+  return CSSPropertyFontUtils::consumeFontFamily(range);
+}
+
+}  // namespace blink