BlendTree spawns errors when selecting a time scale on "Adjust Time Scale" parameter.

To reproduce:
- Create a new project and import the "Mecanim Example Scenes" project from Asset Store
- Open the "Generic Skeleton Example" scene
- In Project Browser, go to Controllers folder and double-click on "MineBot" Animator Controller
- In the Animator window - double-click on "Locotion"
- Select the BlendTree
- Go to Inspector > Adjust Time Scale and select "Homogeneous Speed"
- Observe the following errors in Console:

Quaternion To Matrix conversion failed because input Quaternion is invalid {nan, nan, nan, nan} l=nan
UnityEditor.DockArea:OnGUI()

aabb.IsValid()
UnityEditor.DockArea:OnGUI()

IsFinite(outDistanceForSort)
UnityEditor.DockArea:OnGUI()

IsFinite(outDistanceAlongView)
UnityEditor.DockArea:OnGUI()

Quaternion To Matrix conversion failed because input Quaternion is invalid {nan, nan, nan, nan} l=nan
UnityEditorInternal.AnimatorController:SetAnimatorController(Animator, AnimatorController)
UnityEditor.DockArea:OnGUI()