Transition blend handles should not be inversable

1. What happened
When manipulating the transition blend handles (blue start/end handles on timeline of Inspector), you can move the "start time" past the "end time" and vice-versa. This is not only confusing, but also creates UI issues when moving the handles past the Inspector window frame.

User should never be able to move end time handle before start time handle and vise-versa.
The start time handle should "push" the end time handle, as you drag. Not pop once you release the mouse.
The end time handle should "block" at the start time handle. Not snap back to the start time handle once you release the mouse.

2. How we can reproduce it using the example you attached
Open attached project (or create two clips with a transition)
Select the Transition in the Animator and open the Inspector
>drag blend "start time" handle past the end time handle and release... end time handle snaps to start time handle... this action should "push" end time handle as you drag.
>drag blend "end time" handle past start time handle and release... end time handle snaps to start tome handle... this action should "block" the end time handle at start time handle as you drag.
>When the start or end blend handles are dragged passed the Inspector window frame/UI, this creates a bad/inverted visual representation of the blend, until the UI is clicked and everything snaps back to normal.