Fix some validation errors.

Summary:
This fixes test cases T10019 and T10534

The patch for T10019 should be back-ported to master as well.

Posting via Phab as a way to distribute a patch against the
ghc-7.10 branch, which I don't have push access to.

Test Plan: validate

Reviewers: austin, bgamari

Reviewed By: bgamari

Subscribers: thomie, bgamari, mzero

Differential Revision: https://phabricator.haskell.org/D1036