classList + polyfill error

After 44e875c79059322821916ebaefaa43cd2d2c9c9a i got errors in elem.classList.add(classes[i]); if i have already polifylled array.

See example (see console)

https://jsfiddle.net/Illiax/ad3quksn/9/

I don’t know if i this is intended or not.

[samturrell]

Ok, so this issue appears to be user error, as seen here, you shouldn’t be doing what you’re doing: http://stackoverflow.com/a/948379/1375989

Fix:

if (!Array.prototype.contains) {
    Object.defineProperty(Array.prototype, 'contains', {
        enumerable: false,
        writable: true,
        value: function(element) {
            return !!~this.indexOf(element);
        }
    });
}
if (!Array.prototype.last){
    Object.defineProperty(Array.prototype, 'last', {
        enumerable: false,
        writable: true,
        value: function() {
            return this[this.length - 1];
        }
    })
};

[fmieres]

And thanks for also giving me advice 😃