Introduce internal property sourceMapBaseDirs for Kotlin2JsCompile

Separate property needed to prevent Gradle snapshotting absolute paths
as inputs when passed as compiler argument.
To reduce property visibility to external users put it to the impl class
which will make it invisible in completion but still usable in Kotlin
build.

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/dsl/KotlinJsOptionsImpl.kt

@@ -16,13 +16,19 @@
 
 package org.jetbrains.kotlin.gradle.dsl
 
+import org.gradle.api.file.FileCollection
 import org.jetbrains.kotlin.cli.common.arguments.K2JSCompilerArguments
 
 internal class KotlinJsOptionsImpl : KotlinJsOptionsBase() {
     override var freeCompilerArgs: List<String> = listOf()
 
+    var sourceMapBaseDirs: FileCollection? = null
+
     override fun updateArguments(args: K2JSCompilerArguments) {
         super.updateArguments(args)
         copyFreeCompilerArgsToArgs(args)
+        sourceMapBaseDirs?.let {
+            args.sourceMapBaseDirs = it.asPath
+        }
     }
 }

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/Tasks.kt

@@ -547,6 +547,13 @@ open class Kotlin2JsCompile : AbstractKotlinCompile<K2JSCompilerArguments>(), Ko
             return friendPaths.filter { filter(File(it)) }
         }
 
+    @Suppress("unused")
+    @get:InputFiles
+    @get:Optional
+    @get:PathSensitive(PathSensitivity.RELATIVE)
+    internal val sourceMapBaseDirs: FileCollection?
+        get() = kotlinOptionsImpl.sourceMapBaseDirs
+
     private fun isHybridKotlinJsLibrary(file: File): Boolean =
         LibraryUtils.isKotlinJavascriptLibrary(file) && isKotlinLibrary(file)