Out of curiosity, what is the likely timeline for M3 (and beyond if you're willing to share a tentative plan), and what's lined up for M3?
Incidentally you can use things like filter(), arrayList() now using maven; I just mentionted it in this message.
Just make sure you add the kotlin-js-library dependency in the kotlin-maven-plugin in your maven pom.xml - thats the jar that includes the standard kotlin library so it can be compiled to JS code.
For more on how the JS generation works see the documentation.
M3 is planned to be out late in August/early in September.