texmath-0.13.1.2: test/writer/eqn/msup-01.test

<<< native
[ ESuper (EIdentifier "c") (ENumber "4")
, ESymbol Rel "="
, ESuper
    (EIdentifier "c")
    (EGrouped [ ENumber "4" , EPhantom (EIdentifier "fail") ])
]
>>> eqn
c sup 4 = c sup {4 hphantom fail}