old_contents: Array.prototype.forEach = function(callback) {
  	for(var i = 0, n = this.length; i < n; i++) {
  		callback(this[i], i);
  	}
  }
new_contents: 
  if(!Array.prototype.forEach) Array.prototype.forEach = function(callback) {
  	for(var i = 0, n = this.length; i < n; i++) {
  		callback(this[i], i);
  	}
  }
  
  if(!Object.keys) Object.keys = function(obj) {
  	var keys = [];
  	for(var key in obj) {
  		keys.push(key);
  	}
  	return keys;
  }
  
  
  if(!Date.now) Date.now = function() {
  	return new Date().getTime();
  }
  
  
  
subject: check if date.now exists