Browser's undo state causes weird things with our undo history

Per discussion with @lauriii, this doesn't have to block beta1, though it would be good to fix early in the beta cycle.

Validated this today on 0.x branch and is less confusing than before. Downgrading from beta-target to stable blocker

There is additional work remaining (instead of creating a new revision, it should go back to the previous revision)

hooroomoo → changed the visibility of the branch 3508317-browsers-undo-state to hidden.