[Gradle, JS] Enable Dukat by default with false generateExternals

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/dukat/PackageJsonDukatExecutor.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -30,6 +30,11 @@ class PackageJsonDukatExecutor(
         get() = inputsFile.isFile && prevVersion == version && !packageJsonIsUpdated
 
     fun execute() {
+        if (typeDefinitions.isEmpty()) {
+            npmProject.externalsDirRoot.deleteRecursively()
+            return
+        }
+
         // delete file to run visit on error even without package.json updates
         versionFile.delete()
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/nodejs/NodeJsRootExtension.kt

@@ -44,9 +44,6 @@ open class NodeJsRootExtension(val rootProject: Project) : ConfigurationPhaseAwa
     private val projectProperties = PropertiesProvider(rootProject)
 
     inner class Experimental {
-        val generateKotlinExternals: Boolean
-            get() = projectProperties.jsGenerateExternals == true
-
         val discoverTypes: Boolean
             get() = projectProperties.jsDiscoverTypes == true
     }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/resolver/KotlinRootNpmResolver.kt

@@ -33,9 +33,7 @@ internal class KotlinRootNpmResolver internal constructor(
         get() = nodeJs.rootProject
 
     val plugins = mutableListOf<RootResolverPlugin>().also {
-        if (nodeJs.experimental.generateKotlinExternals) {
+        it.add(DukatRootResolverPlugin(this))
-            it.add(DukatRootResolverPlugin(this))
-        }
     }
 
     enum class State {