return spec of DIFFERENCE omits time!

[meijeru]

Expected behavior

spec-of :difference should contain return: [block! hash! string! bitset! typeset! time!]
since the difference between two date! values is a time! value.

Actual behavior

it contains return: [block! hash! string! bitset! typeset!]

Note that the operation of difference is correct, it is just the spec that is defective.
Note also that difference on dates means something else than subtract or -, since those two (an action and the corresponding op) yield an integer value, namely the number of days, ignoring any time components

Steps to reproduce the problem

execute above code

Red and platform version

any