sequencer: Remove redundant hashmap update (#1583)
sequencer: Remove redundant hashmap update (#1583)

The AddLeafHash method of compact.Tree already sends the leaf hash
through the visitor function, so there is no need to duplicate that.
google/trillian,Martin2112/trillian,AlCutter/trillian,gdbelvin/trillian,daviddrysdale/trillian,gdbelvin/trillian,gdbelvin/trillian,RJPercival/trillian,daviddrysdale/trillian,google/trillian,Martin2112/trillian,Martin2112/trillian,daviddrysdale/trillian,RJPercival/trillian,AlCutter/trillian