Fix awkward double query at finalStep

[hswick]

See basic_verification_game.js query to highStep for an example of this. Solution would be to able to run the test without using the second query.

The issue is because performStepVerification needs lowStep + 1 == highStep. If one doesn't query again, then lowStep doesn't get set.

highStep, lowStep get changed by query/response.

So the fix will belong in the logic in the query method