Don't try to setState after a fragment data update if component not mounted
Don't try to setState after a fragment data update if component not mounted

Summary:
In certain cases, if a RelayContainer is mounted and unmounted quickly, a warning about setting state on an unmounted component is thrown.

This happens due to the fact that in the callback for fragment data updates from the GraphQLStoreQueryResolver, we `setState` without checking whether or not the component is mounted.

This PR resolves that issue.
Closes https://github.com/facebook/relay/pull/730

Reviewed By: yungsters

Differential Revision: D2817201

fb-gh-sync-id: 35eeefeb9affc1eb57d2cad22a9d97e82b4b9d55

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