Turn IC on by default for MPP projects

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

@@ -124,8 +124,9 @@ class MultiplatformGradleIT : BaseGradleIT() {
         }
     }
 
+    // todo: also make incremental compilation test
     @Test
-    fun testNonIncrementalCompileByDefault(): Unit = Project("multiplatformProject", GRADLE_VERSION).run {
+    fun testIncrementalBuild(): Unit = Project("multiplatformProject", GRADLE_VERSION).run {
         val compileCommonTask = ":lib:compileKotlinCommon"
         val compileJsTask = ":libJs:compileKotlin2Js"
         val compileJvmTask = ":libJvm:compileKotlin"

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

@@ -82,7 +82,7 @@ open class KotlinPlatformImplementationPluginBase(platformName: String) : Kotlin
             }
         }
 
-        val incrementalMultiplatform = PropertiesProvider(project).incrementalMultiplatform ?: false
+        val incrementalMultiplatform = PropertiesProvider(project).incrementalMultiplatform ?: true
         project.afterEvaluate {
             project.tasks.withType(AbstractKotlinCompile::class.java).all {
                 if (it.incremental && !incrementalMultiplatform) {