Fix for #12266 : Fixed skipping/cleaning of elements pending animations.

[sreeramu]

Instead of merging existing animation option to new animation options we can merge in reverse and utilize old animation runner.

This PR will fix #12266,#12007 issue.

Example to test:

var app = angular.module("app", ['ngAnimate']);

app.directive('iholder', ['$animate','$timeout', function($animate,$timeout) {
    return {
        restrict: 'EA',
        scope: {},
        template: '<div ng-click="clickHandler()" style="width:100%;height:10em;background-color:red;"></div>',
        replace: true,
        link: function($scope, element, attrs) {
            $scope.clickHandler = function() {
                $animate.addClass(element,'test1');
                $animate.removeClass(element,'test1');
                $animate.addClass(element,'test1');
                $animate.removeClass(element,'test1');
            }
        }
    }
}]);

[Narretz]

Hi, thanks for the PR. Would it be possible for you to add a test for this?

[sreeramu]

@Narretz Test script are updated for this bug.

[matsko]

@sreeramu great work. Could you squash everything together into a single commit and place a commit message that is something like:

fix($animate): ensure that class-based animations are properly applied when cancelled

[matsko]

@sreeramu if you're unable to get to this I could squash everything together and create a commit message for you.

[sreeramu]

@matsko Thank You, i had squash my commits.

[matsko]

Landed as 21d6db3. Excellent work @sreeramu. Than you :)