babylonjs loadingアニメーションを書き直します.

function customLoadingScreen() { 
    console.log("customLoadingScreen creation") 
} 
customLoadingScreen.prototype.displayLoadingUI = function () { 
    console.log("customLoadingScreen loading")  
    loadingScreenDiv.innerHTML = "loading"; 
}; 
customLoadingScreen.prototype.hideLoadingUI = function () { 
    console.log("customLoadingScreen loaded") 
    loadingScreenDiv.style.display = "none";
}; 
var loadingScreen = new customLoadingScreen(); 
engine.loadingScreen = loadingScreen; 
engine.displayLoadingUI();