fix(ngAnimate): setting classNameFilter disables animation inside ng-if

Request Type: bug

How to reproduce: http://plnkr.co/edit/ylFiapyRcSErWC0aC0L0?p=preview

Component(s): ngAnimate

Impact: small

Complexity: medium

This issue is related to: 

**Detailed Description:**

$animate.enter disables all animations on children while the element is being 'animated into' the document. If classNameFilter is set, animations on children are never re-enabled. This fixes that.

**Other Comments:**

Closes #6539