Watch form $valid in a child element in AngularJS

valid.js

  angular.module('foo', []).directive('enableifformisvalid', function() {
    return {
      restrict: 'A',
      require: '^form',
      link: function(scope, element, attrs, formCtrl) {
        window.f = formCtrl;
        scope.$watch(function() {return formCtrl.$valid;}, function(newVal, oldVal) {
          console && console.log('newVal', newVal);
          console && console.log('oldVal', oldVal);
        });
      }
    }
  })