Generate CSSPropertyEquality instead of using hand-updated file.

third_party/WebKit/Source/build/scripts/templates/CSSPropertyEqualityCustom.h.tmpl

+// Copyright 2016 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 CSSPropertyEqualityCustom_h
+#define CSSPropertyEqualityCustom_h
+
+namespace blink {
+
+class ComputedStyle;
+
+class CSSPropertyEqualityCustom {
+public:
+    {% for property_id, property in properties.items() if property.custom_all %}
+    static bool {{property_id}}Equal(const ComputedStyle&, const ComputedStyle& b);
+    {% endfor %}
+};
+
+} // namespace blink
+
+#endif // CSSPropertyEqualityCustom_h