Firefox Webextension in Kotlin

build.gradle

version '1.0-SNAPSHOT'

buildscript {
    ext.kotlin_version = '1.1.60'

    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}

apply plugin: 'kotlin2js'
apply plugin: 'kotlin-dce-js'

repositories {
    mavenCentral()
}

dependencies {
    compile "org.jetbrains.kotlin:kotlin-stdlib-js:$kotlin_version"
}

compileKotlin2Js {
    kotlinOptions.sourceMap = true
}

main.kt

import kotlin.browser.document

fun main(args: Array<String>) {
    document.body?.style?.border = "5px solid red"
}

manifest.json

{
  "manifest_version": 2,
  "name": "Kotlin Borderify",
  "version": "1.0",
  "description": "Adds a red border to kotlinlang.org",
  "content_scripts": [
    {
      "matches": [
        "*://kotlinlang.org/*"
      ],
      "js": [
        "build/classes/kotlin/main/min/kotlin.js",
        "build/classes/kotlin/main/min/kt-borderify.js"
      ]
    }
  ]
}