js/libs/ember-1.5.1.js
function protoWrap(proto, name, callback, isAsync) {
  proto[name] = function() {
    var args = arguments;
    if (isAsync) {
      return callback.apply(this, args);
    } else {
      return this.then(function() {
        return callback.apply(this, args);
      });
    }
  };
}
function protoWrap(proto, name, callback, isAsync) {
  proto[name] = function() {
    var args = arguments;
    if (isAsync) {
      return callback.apply(this, args);
    } else {
      return this.then(function() {
        return callback.apply(this, args);
      });
    }
  };
}
This method is no longer needed But still here for backwards compatibility of helper chaining