class Property 箭头函数体、初始化值、class表达式未支持 #3

测试代码：
class ExtendedAdder extends Adder {
x: number = 0; 初始化值
y: string = '';
// Create a copy of parent before creating our own
private superAdd = this.add;
// Now create our override
add = (b: string): string => { 箭头函数体
return this.superAdd(b);
}
public Members = class { class表达式

}

}