patch applied (ghc): Add a panic for lookupPred EqPred

[Ian Lynagh]

Tue May  6 10:17:49 PDT 2008  Ian Lynagh <igloo at earth.li>
  * Add a panic for lookupPred EqPred
  It's possible that returning Nothing was the right thing to do here,
  but the comment and variable name indicated that it was written for
  implicit parameters, so make it a panic for now just in case.

    M ./compiler/typecheck/Inst.lhs -1 +2

View patch online:
http://darcs.haskell.org/ghc/_darcs/patches/20080506171749-3fd76-6e88dd1b5d1c5fa62388393f914de2c659631045.gz