Made check for pending animations in SC.View's adjust() method safer

In IE 9, it can happen that SC.View's `adjust()` method will try to access a property of `_pendingAnimations` while `_pendingAnimations` is set to `null`.

![screen shot 2014-10-13 at 11 26 43](https://cloud.githubusercontent.com/assets/446063/4611596/e1112cfa-52bc-11e4-8082-5d64431e7e64.png)

I fixed this by checking for `_pendingAnimations` first.

Let me know if this makes sense for you.