According to the NYT it is actually "20 F-35s when the final peace deal is signed" i.e. no final treaty = no shiny new jets. The only thing that Netanyahu "gets" for the 90 day freeze is a promise not to waive the US veto during the period that the negotiations are taking place.
High Court: Illegal West Bank homes to be demolished (Haaretz)
from the article: Obama has made Netanyahu an offer he can't refuse