覆盖fairygui的getChild方法，提高性能

initFairyGUI.ts

// 初始化Fairygui时调用
const rawNewObject = fgui.UIObjectFactory.newObject;
fgui.UIObjectFactory.newObject = (pi: fgui.PackageItem): fgui.GObject => {
    if (!pi.extensionType && pi.objectType === fgui.ObjectType.Component) {
        const skin = new FairySkinBase();
        skin.packageItem = pi;
        return skin;
    }
    return rawNewObject(pi);
};