fix flow error in runTestSuite.js
fix flow error in runTestSuite.js

Summary: This was causing an error when Flow checking this file.

Reviewed By: gabelevi

Differential Revision: D13675922

fbshipit-source-id: 369a745b4c42724a298cc6f2058e67cb05cd90a3

popham/flow,samwgoldman/flow,facebook/flow,AgentME/flow,facebook/flow,mroch/flow,mroch/flow,popham/flow,popham/flow,AgentME/flow,samwgoldman/flow,facebook/flow,gabelevi/flow,samwgoldman/flow,samwgoldman/flow,mroch/flow,facebook/flow,samwgoldman/flow,gabelevi/flow,gabelevi/flow,samwgoldman/flow,gabelevi/flow,gabelevi/flow,AgentME/flow,mroch/flow,AgentME/flow,facebook/flow,popham/flow,popham/flow,gabelevi/flow,gabelevi/flow,mroch/flow,samwgoldman/flow,popham/flow,popham/flow,facebook/flow,facebook/flow,mroch/flow,AgentME/flow,mroch/flow