[hack] Use Core for Json
[hack] Use Core for Json

Reviewed By: @​bpr

Differential Revision: D2484098

jgrund/flow,AgentME/flow,jgrund/flow,jamesgpearce/flow,MichaelDeBoey/flow,jgrund/flow,MichaelDeBoey/flow,AgentME/flow,mcanthony/flow-type,graue/flow,facebook/flow,gabelevi/flow,AgentME/flow,samwgoldman/flow,shiftcars/flow,jeffutter/flow,claudiopro/flow,chenglou/flow,jeffmo/flow,graue/flow,samwgoldman/flow,popham/flow,TiddoLangerak/flow,fletcherw/flow,gabelevi/flow,gabro/flow,facebook/flow,popham/flow,popham/flow,MichaelDeBoey/flow,mroch/flow,d14b3l/flow,samwgoldman/flow,d14b3l/flow,jdelStrother/flow,Eyyub/flow,popham/flow,claudiopro/flow,shiftcars/flow,jeffmo/flow,AprilArcus/flow,d14b3l/flow,jamesgpearce/flow,shiftcars/flow,OCamlPro/flow,gabelevi/flow,mroch/flow,fletcherw/flow,jamesgpearce/flow,AgentME/flow,jeffmo/flow,popham/flow,gabro/flow,d14b3l/flow,jdelStrother/flow,graue/flow,asivitz/flow,shiftcars/flow,jeffutter/flow,nmote/flow,ylu1317/flow,JohnyDays/flow,jgrund/flow,nmote/flow,gabro/flow,TiddoLangerak/flow,MichaelDeBoey/flow,ylu1317/flow,mcanthony/flow-type,mroch/flow,claudiopro/flow,facebook/flow,JonathanUsername/flow,jgrund/flow,d14b3l/flow,jeffutter/flow,MichaelDeBoey/flow,JonathanUsername/flow,gabelevi/flow,claudiopro/flow,nmote/flow,claudiopro/flow,TiddoLangerak/flow,fletcherw/flow,ForbesLindesay/flow,samwgoldman/flow,asivitz/flow,jdelStrother/flow,Eyyub/flow,fletcherw/flow,graue/flow,ForbesLindesay/flow,nmote/flow,nmote/flow,jamesgpearce/flow,shiftcars/flow,ylu1317/flow,gabelevi/flow,chenglou/flow,TiddoLangerak/flow,gabelevi/flow,facebook/flow,JonathanUsername/flow,JonathanUsername/flow,chenglou/flow,JonathanUsername/flow,jamesgpearce/flow,ForbesLindesay/flow,jdelStrother/flow,AprilArcus/flow,facebook/flow,Eyyub/flow,jeffutter/flow,mroch/flow,facebook/flow,jdelStrother/flow,mcanthony/flow-type,jdelStrother/flow,graue/flow,graue/flow,ForbesLindesay/flow,JohnyDays/flow,OCamlPro/flow,chenglou/flow,asivitz/flow,jgrund/flow,AprilArcus/flow,d14b3l/flow,ylu1317/flow,AprilArcus/flow,gabro/flow,Eyyub/flow,mroch/flow,gabelevi/flow,nmote/flow,cesarandreu/flow,jeffmo/flow,nmote/flow,cesarandreu/flow,chenglou/flow,OCamlPro/flow,samwgoldman/flow,mcanthony/flow-type,JonathanUsername/flow,AprilArcus/flow,OCamlPro/flow,samwgoldman/flow,AgentME/flow,AprilArcus/flow,chenglou/flow,JohnyDays/flow,JonathanUsername/flow,fletcherw/flow,jamesgpearce/flow,ylu1317/flow,ForbesLindesay/flow,cesarandreu/flow,jamesgpearce/flow,mroch/flow,gabro/flow,jeffmo/flow,JohnyDays/flow,shiftcars/flow,facebook/flow,cesarandreu/flow,asivitz/flow,ForbesLindesay/flow,mroch/flow,jeffmo/flow,fletcherw/flow,TiddoLangerak/flow,samwgoldman/flow,popham/flow,gabro/flow,popham/flow