naked React expression is not longer required in es6-babel-react-flux-karma sample

[johnnyreilly]

@mhegazy notified me but I can't remember where he raised it. Opening this issue to remind me to pull the expression out. I think this may depend on TS 1.8 which hasn't yet shipped. So will look to do as soon as it gets released.

https://github.com/Microsoft/TypeScriptSamples/tree/master/es6-babel-react-flux-karma