[PR] Correct the return type of events$EventEmitter#setMaxListeners
[PR] Correct the return type of events$EventEmitter#setMaxListeners

Summary:
https://nodejs.org/api/events.html#events_emitter_setmaxlisteners_n
Closes https://github.com/facebook/flow/pull/4292

Reviewed By: zertosh

Differential Revision: D5366259

Pulled By: nmote

fbshipit-source-id: 36672c3974386bd04c37f9b4155e4a503ae97380

TiddoLangerak/flow,gabelevi/flow,nmote/flow,samwgoldman/flow,mroch/flow,MichaelDeBoey/flow,JonathanUsername/flow,popham/flow,MichaelDeBoey/flow,JonathanUsername/flow,TiddoLangerak/flow,TiddoLangerak/flow,MichaelDeBoey/flow,facebook/flow,mroch/flow,ylu1317/flow,claudiopro/flow,facebook/flow,jamesgpearce/flow,MichaelDeBoey/flow,claudiopro/flow,ylu1317/flow,popham/flow,AgentME/flow,nmote/flow,nmote/flow,jamesgpearce/flow,samwgoldman/flow,facebook/flow,popham/flow,gabelevi/flow,nmote/flow,nmote/flow,ylu1317/flow,mroch/flow,facebook/flow,gabelevi/flow,claudiopro/flow,MichaelDeBoey/flow,TiddoLangerak/flow,gabelevi/flow,TiddoLangerak/flow,mroch/flow,nmote/flow,JonathanUsername/flow,jamesgpearce/flow,ylu1317/flow,JonathanUsername/flow,samwgoldman/flow,JonathanUsername/flow,ylu1317/flow,gabelevi/flow,JonathanUsername/flow,popham/flow,mroch/flow,gabelevi/flow,jamesgpearce/flow,nmote/flow,JonathanUsername/flow,popham/flow,AgentME/flow,samwgoldman/flow,samwgoldman/flow,facebook/flow,AgentME/flow,AgentME/flow,jamesgpearce/flow,mroch/flow,AgentME/flow,jamesgpearce/flow,popham/flow,facebook/flow,gabelevi/flow,claudiopro/flow,popham/flow,facebook/flow,jamesgpearce/flow,claudiopro/flow,mroch/flow,samwgoldman/flow,samwgoldman/flow