Implemented the CSSPropertyAPI for the font-family property.

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

Index: third_party/WebKit/Source/core/css/properties/CSSPropertyAPIFontFamily.cpp
diff --git a/third_party/WebKit/Source/core/css/properties/CSSPropertyAPIFontFamily.cpp b/third_party/WebKit/Source/core/css/properties/CSSPropertyAPIFontFamily.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..b8989bf968fcf957d2c86018121f4fe0bf32c72d
--- /dev/null
+++ b/third_party/WebKit/Source/core/css/properties/CSSPropertyAPIFontFamily.cpp
@@ -0,0 +1,20 @@
+// 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