Update `PropertySpec`.
Update `PropertySpec`.

calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,sandyway/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,ReactiveCocoa/ReactiveSwift,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,ohwutup/ReactiveCocoa,ikesyo/ReactiveCocoa,walkingsmarts/ReactiveCocoa,victorlin/ReactiveCocoa,ohwutup/ReactiveCocoa,ikesyo/ReactiveCocoa,ohwutup/ReactiveCocoa,victorlin/ReactiveCocoa,victorlin/ReactiveCocoa,sandyway/ReactiveCocoa,sandyway/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,calebd/ReactiveCocoa