texmath-0.12.5: test/writer/tex/msup-10.test

<<< native
[ ESuper (EIdentifier "S") (ENumber "2")
, ESymbol Rel "="
, EUnder
    False
    (ESuper (EIdentifier "S") (ENumber "2"))
    (EPhantom (EIdentifier "fail"))
]
>>> tex
S^{2} = \underset{\phantom{fail}}{S^{2}}