I submitted a KEEP that aims to solve problems with Implementation by Delegation (interface delegates) a few days ago.
Discussion is ongoing, however, I know nothing about Kotlin that is JS-specific, such as how code generation works.
If anyone interested and knowledgeable is willing to put in the time, please do take a look at the proposal and detail JS-specific code generation that would be aimed at achieving the same as described in the JVM Codegen section. I would really appreciate it.
Hoping it can be as complete as possible before JB team has a look at it.
Of course, any feedback related to this KEEP is very welcome.
Here's the link: https://github.com/Kotlin/KEEP/issues/155