Validators currently call VerifyVoteExtension on all precommits that they receive for the current height. However, we currently do not use the vote extension data when reconstructing the lastCommit and passing the extended data to the application during PrepareProposal. This suggests that we can forgo calling the application with this data that is inevitably not going to be used. We should also consider dropping this from the ExtendedCommit that is stored in the block store.