Kotlin2Js Gradle plugin

I'm not exactly sure what you mean. Let me explain the use-case I tried to solve here, maybe that's an answer; if not, please clarify.

There are two things you may want to do with source maps. One, use them locally. In this case it doesn't matter where the Kotlin sources are, the browser will find them over the `file://` protocol. Two, distribute the source-map and Kotlin sources with the project; either as a debug build of the application, or as an example of kotlin2js. In this case the Kotlin sources need to be copied to a place the sourcemap can reference; also it needs to be edited to point to paths relative to the sourcemap (that's what `createRewritePathsInSourceMapTask` does).