Support Kotlin/JS

[ankushg]

Now that 2.0 is in alpha, we can write Spek tests in common modules and run them via JUnit when building/testing jvm modules.

It would be amazing to run those same common Spek tests when building/testing for js modules as well.

I realize this is probably a little far away, but I figured it couldn't hurt to get the discussion started on what a Javascript test runner for Spek could look like.

[raniejade]

Haven't thought about it that much, but in the case for kotlin-test support is built-in into the kotlin compiler itself.