The only real use case left for TypeGuard was the renaming inside the
LoadElimination, but this case only occurs in dead code (guarded by a
previous Check), so it's not relevant, and we can drop the TypeGuard
operator completely.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2108793003
Cr-Commit-Position: refs/heads/master@{#37361}