once-show should hide undefined elements

[NinjaCross]

I think that once-show should hide undefined elements before adding a watch for them.
This will satisfy the case when a data member is purposely omitted from the data model for optimization purposes.
This small changes in code did the trick for me:

  function setOneTimeBinding($scope, element, watch, watcherParser, bindingParser, done,definitioName) {
    // get value to watch
    var watchingValue = watcherParser($scope);
    // if we have a valid value, render the binding's value
    if (watchingValue !== undefined) {
      // if watching and binding $parsers are the same, use watching's value, else $parse the new value
      return done(element, watcherParser == bindingParser ? watchingValue : bindingParser($scope));
    }

    if (definitioName == 'onceShow')
    {
       $(element[0]).hide();
    }


    // we do not have a valid value, so we register a $watch
    var watcherRemover = $scope.$watch(watch, function (newValue) {
      // wait until we have a valid value
      if (newValue == undefined) return;
      // remove this $watch
      removeWatcher();
      // if watching and binding $parsers are the same, use watching's value, else $parse the new value
      return done(element, watcherParser == bindingParser ? newValue : bindingParser($scope));
    });

    function removeWatcher() {
      if (watcherRemover) {
        watcherRemover();
      }
    }

    $scope.$on("$destroy", removeWatcher);
  }

  var once = angular.module('once', []);

  function makeBindingDirective(definition) {
    once.directive(definition.name, ['$parse', function ($parse) {
      return {
        priority: definition.priority || 0,
        link: function ($scope, element, attrs) {
          var watch = attrs.onceWaitFor || attrs[definition.name];
          var watcherParser = $parse(watch);
          var bindingParser = attrs.onceWaitFor ? $parse(attrs[definition.name]) : watcherParser;
          setOneTimeBinding($scope, element, watch, watcherParser, bindingParser, definition.binding, definition.name);
        }
      };
    }]);
  }