texmath-0.12.5: test/writer/eqn/msub-10.test

<<< native
[ ESub (EIdentifier "S") (ENumber "5")
, ESymbol Rel "="
, EUnder
    False
    (ESub (EIdentifier "S") (ENumber "5"))
    (EPhantom (EIdentifier "t"))
]
>>> eqn
S sub 5 = {S sub 5} from {hphantom t}