texmath-0.12.5: test/roundtrip/mrootSscriptlevel4.native

[ ERoot
    (EFraction NormalFrac (EIdentifier "x") (ENumber "3"))
    (EGrouped
       [ EIdentifier "x"
       , ESymbol Bin "-"
       , EFraction NormalFrac (EIdentifier "x") (ENumber "3")
       ])
, ESymbol Bin "+"
, ERoot
    (EFraction NormalFrac (EIdentifier "x") (ENumber "3"))
    (EGrouped [ EIdentifier "x" , ESymbol Bin "-" , ENumber "3" ])
, ESymbol Bin "+"
, ERoot
    (EFraction NormalFrac (EIdentifier "x") (ENumber "3"))
    (EGrouped [ EIdentifier "x" , ESymbol Bin "-" , ENumber "3" ])
, ESymbol Bin "+"
, EFraction NormalFrac (EIdentifier "x") (ENumber "3")
]