message: Fix fast sync compilation.
diff: @@ -51,7 +51,7 @@ impl<I: Clone + PartialEq + 'static> LinearChainFastSync<I> {
  _chainspec: &Chainspec,
  _storage: &Storage,
  init_hash: Option<BlockHash>,
  - _highest_block_header: Option<BlockHeader>,
  + _highest_block: Option<Block>,
  genesis_validator_weights: BTreeMap<PublicKey, U512>,
  _next_upgrade_activation_point: Option<ActivationPoint>,
  ) -> Result<(Self, Effects<Event<I>>), Err>
  