Fix error Utils not defined in Http module serve

[tino415]

When tried to use serve function from module Http I get

ReferenceError: Utils is not defined
    at Object.callback (/mnt/old/home/martin/Projects/experiments/elm-node/example/example-http.js:3399:73)
    at step (/mnt/old/home/martin/Projects/experiments/elm-node/example/example-http.js:1906:39)
    at Timeout.work [as _onTimeout] (/mnt/old/home/martin/Projects/experiments/elm-node/example/example-http.js:1964:15)
    at ontimeout (timers.js:386:14)
    at tryOnTimeout (timers.js:250:5)
    at Timer.listOnTimeout (timers.js:214:5)

I expect that it is supposed to be _elm_lang$core$Native_Utils