FEFuncBElement 构造函数
实现
factory FEFuncBElement() =>
    _SvgElementFactoryProvider.createSvgElement_tag("feFuncB")
        as FEFuncBElement;factory FEFuncBElement() =>
    _SvgElementFactoryProvider.createSvgElement_tag("feFuncB")
        as FEFuncBElement;