/*global window */
/**
* RequestAnimationFrame shim layer with setTimeout fallback
* @param {function} callback The function to call.
* @returns {function|Object} An animation frame or a timeout object.
*/
window.requestAnimFrame = (function(callback){
'use strict';
return window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();