Cantor Fitzgerald LP invoked two contractual devices when six of its partners quit. There was a typical set of restrictive covenants, which were knocked out as unreasonable by a Delaware chancellor. Then there was a “conditioned payment device” — triggered by any “competitive activity” — that authorized forfeiture of capital accounts and earned compensation ranging from $96,651 to almost $5.5 million. The forfeiture-for-competition provision, cleverly crafted as a condition precedent, applied even if the competition didn’t …