Cordova.js external app not working

–> platforms/ios/www/cordova.js file in the

I deleted the following code
my app worked but css not included
code line 1872-1887
/**
*Extends a child object from a parent object using classical inheritance pattern.
*/
utils.extend=(function(){
//proxy used to establish prototype chain
var F = function () {};
//extend Child from parent

return function (Child,Parent){
F.prototype= Parent.prototype;
Child.prototype= new F();
Child.super= Parent.prototype;
Child.prototype.constructor = Child;
};
}());