verify if KT-23178 (isInstace in JS) is really fixed

[robstoll]

Platform (jvm, js, android): js
Extension (none, kotlin 1.3, jdk8): none

Code related feature

We have currently a workaround implemented for

equals in KClass in JS not symmetric. Not working isInstance
https://youtrack.jetbrains.com/issue/KT-23178

The workaround made sure that casting in JS works as expected. JetBrains claims to have fixed this issue. We would like to be sure that this is really the case.
We should have implemented corresponding regression tests and there the things you need to do are:

• rewrite core/api/atrium-core-api-js/src/main/kotlin/ch/tutteli/atrium/core/polyfills/kClassExtensions.kt according to the explanation given in the TODO
• run the KClassCastTest via gradle gr :atrium-core-api-js:test and verify that it is still green after your change.

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[Valefant]

I would like to take this one