Provide default output JS file in Kotlin Gradle plugin

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/Kotlin2JsGradlePluginIT.kt

@@ -66,12 +66,12 @@ class Kotlin2JsGradlePluginIT : BaseGradleIT() {
     }
 
     @Test
-    fun testNoOutputFileFails() {
+    fun testDefaultOutputFile() {
         val project = Project("kotlin2JsNoOutputFileProject", "2.10")
+
         project.build("build") {
-            assertFailed()
-            assertReportExists()
-            assertContains("compileKotlin2Js.kotlinOptions.outputFile should be specified.")
+            assertSuccessful()
+            assertFileExists("build/classes/main/kotlin2JsNoOutputFileProject_main.js")
         }
     }