[Gradle, JS] Fix DSL for JVM/JS wizard

#KT-36889 fixed

idea/idea-gradle/src/org/jetbrains/kotlin/idea/configuration/KotlinGradleWebMultiplatformModuleBuilder.kt

@@ -213,6 +213,7 @@ class KotlinGradleWebMultiplatformModuleBuilder : KotlinGradleAbstractMultiplatf
     }
 
     override fun buildMultiPlatformPart(): String {
+        //language=Gradle
         return """
             def ktor_version = '1.1.3'
             def logback_version = '1.2.3'
@@ -222,6 +223,7 @@ class KotlinGradleWebMultiplatformModuleBuilder : KotlinGradleAbstractMultiplatf
                 js {
                     browser {
                     }
+                    produceExecutable()
                 }
                 sourceSets {
                     $commonSourceName {