Summary:
In MountingCoordinator override mode (used in LayoutAnimations) we must set the start and end `diff` time when no real diff happens, otherwise we will hit an assert in telemetry later.
I also ensure that the TransactionNumber is incremented in that case.
Changelog: [Internal]
Reviewed By: shergin
Differential Revision: D23746684
fbshipit-source-id: b1fe3864e453fdba89d43cc827bd37434abf7a4d