[easy] Fix typedJSON example
[easy] Fix typedJSON example

Summary:Becuase `typeof x === 'object'` refines to `AnyObject`, the `x[k]` expression
yielded an `any`, which was directly assignable to the expected `JSON` value of
`o[k]`.

This refinement behavior is a bit surprising, and I posed a question regarding
its behavior already: https://github.com/facebook/flow/issues/1429

Reviewed By: mroch

Differential Revision: D3006763

fb-gh-sync-id: 16b9de0402a8d543d3dd7296c29de3ce8a098cf1
shipit-source-id: 16b9de0402a8d543d3dd7296c29de3ce8a098cf1

d14b3l/flow,fletcherw/flow,nmote/flow,popham/flow,nmote/flow,fletcherw/flow,shiftcars/flow,samwgoldman/flow,ForbesLindesay/flow,facebook/flow,gabelevi/flow,jeffmo/flow,gabro/flow,samwgoldman/flow,ForbesLindesay/flow,MichaelDeBoey/flow,jamesgpearce/flow,jamesgpearce/flow,mroch/flow,mroch/flow,jgrund/flow,samwgoldman/flow,facebook/flow,gabelevi/flow,ForbesLindesay/flow,AprilArcus/flow,d14b3l/flow,facebook/flow,d14b3l/flow,graue/flow,jdelStrother/flow,JonathanUsername/flow,fletcherw/flow,MichaelDeBoey/flow,chenglou/flow,TiddoLangerak/flow,samwgoldman/flow,gabro/flow,mroch/flow,facebook/flow,AprilArcus/flow,ylu1317/flow,AgentME/flow,claudiopro/flow,graue/flow,ForbesLindesay/flow,shiftcars/flow,AprilArcus/flow,cesarandreu/flow,ylu1317/flow,fletcherw/flow,ylu1317/flow,gabelevi/flow,JonathanUsername/flow,mroch/flow,graue/flow,cesarandreu/flow,jeffmo/flow,TiddoLangerak/flow,fletcherw/flow,shiftcars/flow,mroch/flow,gabro/flow,JonathanUsername/flow,popham/flow,TiddoLangerak/flow,d14b3l/flow,gabelevi/flow,TiddoLangerak/flow,popham/flow,cesarandreu/flow,TiddoLangerak/flow,ylu1317/flow,jgrund/flow,popham/flow,jdelStrother/flow,facebook/flow,AgentME/flow,MichaelDeBoey/flow,jamesgpearce/flow,cesarandreu/flow,gabelevi/flow,chenglou/flow,AprilArcus/flow,claudiopro/flow,jdelStrother/flow,MichaelDeBoey/flow,JonathanUsername/flow,JonathanUsername/flow,claudiopro/flow,chenglou/flow,chenglou/flow,gabro/flow,jgrund/flow,nmote/flow,graue/flow,popham/flow,shiftcars/flow,gabro/flow,jamesgpearce/flow,gabelevi/flow,mroch/flow,d14b3l/flow,nmote/flow,chenglou/flow,ylu1317/flow,AprilArcus/flow,JonathanUsername/flow,nmote/flow,jdelStrother/flow,facebook/flow,AgentME/flow,jgrund/flow,graue/flow,fletcherw/flow,mroch/flow,MichaelDeBoey/flow,jamesgpearce/flow,jeffmo/flow,JonathanUsername/flow,AgentME/flow,jeffmo/flow,jgrund/flow,jdelStrother/flow,ForbesLindesay/flow,facebook/flow,AprilArcus/flow,popham/flow,ForbesLindesay/flow,jamesgpearce/flow,claudiopro/flow,nmote/flow,samwgoldman/flow,shiftcars/flow,d14b3l/flow,samwgoldman/flow,jdelStrother/flow,jeffmo/flow,AgentME/flow,claudiopro/flow,jeffmo/flow,jamesgpearce/flow,nmote/flow,jgrund/flow,samwgoldman/flow,chenglou/flow,graue/flow,popham/flow,gabro/flow,gabelevi/flow,shiftcars/flow