[Gradle, JS] Use node_modules dir existence as marker of up-to-date

^KT-34014 fixed
^KT-49505 fixed

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/kotlin-js-test-webpack-config/build.gradle.kts

@@ -20,7 +20,6 @@ kotlin {
             inputFileProperty.set(provider { compilation.npmProject.require("webpack/bin/webpack.js") }.map { RegularFile { File(it) } })
             dependsOn("browserDevelopmentWebpack")
             val configFile = tasks.named<org.jetbrains.kotlin.gradle.targets.js.webpack.KotlinWebpack>("browserDevelopmentWebpack").map { it.configFile }.get()
-            configFile.parentFile.listFiles().forEach { println(it)}
             args("configtest")
             args(configFile.absolutePath)
         }

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

@@ -31,6 +31,19 @@ open class KotlinNpmInstallTask : DefaultTask() {
     @Input
     val args: MutableList<String> = mutableListOf()
 
+    @get:Internal
+    val nodeModulesDir: File by lazy {
+        (nodeJs ?: unavailableValueError("nodeJs"))
+            .rootPackageDir
+            .resolve("node_modules")
+    }
+
+    init {
+        outputs.upToDateWhen {
+            nodeModulesDir.isDirectory
+        }
+    }
+
     @Suppress("unused")
     @get:PathSensitive(PathSensitivity.ABSOLUTE)
     @get:IgnoreEmptyDirectories