BlendTree is completely broken when changing the Compute Threshold parameter to Speed.

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 and un-tick the box for "Automate Thresholds"
- On "Compute Thresholds", select Speed from drop down menu
- Observe that the BlendTree is now in an unusable state

Please see attached screen shot for details.