Changes all instances of $animate.enter() to follow angular 1.3.x semantics without breaking 1.2.x

[assisrafael]

According to the angular migration guide the $animate.enter() method behavior has changed. This change causes flickering for some Angular 1.3.x apps. I was not able to isolate a small scenario.

[chieffancypants]

Nice! Thanks!

[joaovieira]

@chieffancypants @assisrafael this does not take into account if parent does not have children. In these situations, the bar is never appended.

According to angular's $AnimateProvider.$get.enter code:

enter: function(element, parent, after, options) {
        applyStyles(element, options);
        after ? after.after(element)
              : parent.prepend(element);
        return asyncPromise();
      }

If parent doesn't have children, the after element will be defined but empty.

[chieffancypants]

@joaovieira what do you suggest?

[joaovieira]

@chieffancypants I had another look... Although the migration document suggests to use angular.element() with the lastChild, it is actually not needed, since $animate.enter() already prepares this for us:
https://github.com/angular/bower-angular-animate/blob/v1.3.15/angular-animate.js#L950
https://github.com/angular/bower-angular-animate/blob/v1.3.15/angular-animate.js#L471

Also, if there's no children in the parent element:
$parent[0].lastChild -> null
angular.element($parent[0].lastChild) -> []

Because of this, using simply:

$animate.enter(loadingBarContainer, $parent, $parent[0].lastChild);

Will do. If the lastChild is null, it remains null until the end and the bar is prepended in the parent, if lastChild exists the bar is prepended after it. But if it's [] it does nothing :)

I can create the PR with the test case if needed.

[joaovieira]

Sorry, seems like that won't work with the default $animate (funny that the ngAnimateMock only delegates to the default and doesn't really behave like the real implementation...). I'd then suggest doing the same check ngAnimate does?

$animate.enter(loadingBarContainer, $parent, $parent[0].lastChild && angular.element($parent[0].lastChild));

[assisrafael]

I think you should start by writing a test case that breaks. It will help in your search for the proper solution.

[joaovieira]

PR #218