Update code to work with scala.rx 0.3.2

[drhumlen]

No description provided.

[drhumlen]

I think there's been some changes to ScalaJs. It seems that you now get the error: Error: Cannot find module 'jsdom' when you have requiresDOM := true in your build.sbt, which is why the build is breaking...

I fixed it on my machine by just doing a npm install jsdom from the project root folder, but I'm not sure if it's the recommended way to do it. If it is, I guess we could add npm install jsdom as one of the steps in .travis.yml

[drhumlen]

Found this: scala-js/scala-js#2642

It seems npm install jsdom is the way to do it. Added it to travis.yml now. Let's hope it works 🙏

[rtimush]

Thank you, this was a huge work!