[Angular] AngularJS: Error: event is undefined (Firefox only)

在fireFox中使用AngularJS，會出現event is undefined 的錯誤，

ex:

< button ng-click="addStatus($event)"> ADD < /button>    

$scope.addStatus = function ($event){

    $(event.target).addClass('added-status'); 
}

需要修正為

< button ng-click="addStatus($event)"> ADD < /button>    

$scope.addStatus = function (event){

    $(event.target).addClass('added-status'); 
}