You can just go back to the 3.4.02 AnimationState (with minimal changes) and continue using the 3.5 editor and the rest of the 3.5 runtimes.
December 13th, 2016, 11:56 pm
I gave the modifications I posted a whirl and it didn't work as intended. I tested it when I wrote it, so that's odd. Here's the fix:
https://gist.github.com/NathanSweet/3aaeb489c2e8cdca76b31f5ae87f2b8b
This is an experimental AnimationState which fixes dipping and disables multiple mixing from. See the Gist history to go from the master branch AnimationState, to one which fixes dipping, to one which also disables multiple mixing from.
You should not see dipping, but you will see snapping when interrupting a mix because there is no multiple mixing from. That snapping happened with the old AnimationState, so you should be no worse off. Hopefully this helps!