Get in-scope set right in top_instantiate
Get in-scope set right in top_instantiate

...thereby being able to replace substThetaUnchecked
with substTheta

(cherry picked from commit 7afb7adf45216701e4f645676ecc0668f64b424d)

GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc