Type operators are not accepted as variables in contexts

The following code is accepted by 7.4.1 (and 7.2/7.0/6.12), but rejected by HEAD:

$ ghci-7.5.20120402 -XTypeOperators
GHCi, version 7.5.20120402: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
λ> import Control.Category
λ> let f :: Category (->>) => (a ->> b); f = undefined

<interactive>:3:19: Not in scope: type constructor or class `->>'

<interactive>:3:31: Not in scope: type constructor or class `->>'

Trac metadata

Trac field	Value
Version	7.5
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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