refreshBrowsers should work in jvm-js-shared example

[cdietze]

The refreshBrowsers feature does not work in the jvm-js-shared branch example.
When sbt is run using ~re-start the expected behavior is that the browser reloads after a change to the JS-file. However, a manual refresh is needed.

I assume this is because refreshBrowsers is by default triggered after fastOptJS, but this is too early and we would need a trigger after the server restarted.
However, what surprises me that if I make another the change the refresh does not pick up the first change.