Relay: Stop Using Promise#finally
Relay: Stop Using Promise#finally

Summary: `Promise#finally` is not part of the spec. We don't need it anyway.

Reviewed By: josephsavona

Differential Revision: D2617784

fb-gh-sync-id: 6fcfe94b10ad91ebde768145190034d2f6b84d42

mroch/relay,cpojer/relay,zpao/relay,NevilleS/relay,josephsavona/relay,NevilleS/relay,mroch/relay,michaelchum/relay,voideanvalue/relay,chirag04/relay,rosskevin/relay,iamchenxin/relay,venepe/relay,voideanvalue/relay,facebook/relay,gabelevi/relay,Aweary/relay,yungsters/relay,mroch/relay,dbslone/relay,voideanvalue/relay,venepe/relay,cesarandreu/relay,xuorig/relay,xuorig/relay,chentsulin/relay,michaelchum/relay,xuorig/relay,benjaminogles/relay,kassens/relay,atxwebs/relay,cpojer/relay,facebook/relay,cpojer/relay,forter/generic-relay,wincent/relay,cesarandreu/relay,chentsulin/relay,xuorig/relay,gabelevi/relay,voideanvalue/relay,yungsters/relay,josephsavona/relay,cpojer/relay,heracek/relay,xuorig/relay,kassens/relay,kassens/relay,benjaminogles/relay,chentsulin/relay,atxwebs/relay,kassens/relay,wincent/relay,freiksenet/relay,NevilleS/relay,andimarek/generic-relay,benjaminogles/relay,wincent/relay,josephsavona/relay,heracek/relay,cesarandreu/relay,facebook/relay,kassens/relay,xuorig/relay,venepe/relay,gabelevi/relay,iamchenxin/relay,facebook/relay,andimarek/generic-relay,michaelchum/relay,dbslone/relay,wincent/relay,chirag04/relay,zpao/relay,facebook/relay,rosskevin/relay,apalm/relay,Aweary/relay,wincent/relay,atxwebs/relay,iamchenxin/relay,voideanvalue/relay,facebook/relay,voideanvalue/relay,Aweary/relay,kassens/relay,andimarek/generic-relay,apalm/relay,freiksenet/relay,iamchenxin/relay,wincent/relay,chirag04/relay,apalm/relay,freiksenet/relay,atxwebs/relay,yungsters/relay,heracek/relay,zpao/relay