Function removeChild

packages/fairygui/src/display/DisplayObject.ts:360–365

* Remove a child display object * 移除子显示对象

(child: DisplayObject)

     * 移除子显示对象
     */
    public removeChild(child: DisplayObject): void {
        const index = this._children.indexOf(child);
        if (index >= 0) {
            this.removeChildAt(index);
        }
    }

    /**
     * Remove child at specific index