FEFuncGElement 构造函数
实现
factory FEFuncGElement() =>
    _SvgElementFactoryProvider.createSvgElement_tag("feFuncG")
        as FEFuncGElement;factory FEFuncGElement() =>
    _SvgElementFactoryProvider.createSvgElement_tag("feFuncG")
        as FEFuncGElement;