Merge pull request jashkenas#619 from braddunbar/invoke

Remove unnecessary code as per jashkenas#618.

underscore.js

@@ -213,7 +213,7 @@
   _.invoke = function(obj, method) {
     var args = slice.call(arguments, 2);
     return _.map(obj, function(value) {
-      return (_.isFunction(method) ? method || value : value[method]).apply(value, args);
+      return (_.isFunction(method) ? method : value[method]).apply(value, args);
     });
   };