Add some array methods for List

lib/list.js

@@ -115,6 +115,13 @@ if (_) {
     });
 }
 
+['slice', 'forEach'].forEach(function (method) {
+    var slice = [].slice;
+    List.prototype[method] = function () {
+        return Array.prototype[method].apply(this.items, slice.call(arguments));
+    };
+});;
+
 List.prototype.toObject = function() {
     return this.items;
 };
@@ -154,10 +161,6 @@ List.prototype.remove = function(obj) {
     }
 };
 
-List.prototype.forEach = function(cb) {
-    this.items.forEach(cb);
-};
-
 List.prototype.sort = function(cb) {
     return this.items.sort(cb);
 };