[css-cascade-4] ''revert'' missing in the definition of 'all'

Cascade level 4 defines all as "initial | inherit | unset". Is there any reason that's not "initial | inherit | unset | revert" ?

''revert'' is defined as a global keyword later in the same spec, and 'all' is supposed to accept all global keywords, so I guess it's just an omission.

 - Florian