Override/Implement: Drop 'impl' modifier for non-impl class members

#KT-18469 Fixed

idea/idea-core/src/org/jetbrains/kotlin/idea/core/overrideImplement/OverrideMemberChooserObject.kt

@@ -110,6 +110,10 @@ fun OverrideMemberChooserObject.generateMember(targetClass: KtClassOrObject, cop
         else -> error("Unknown member to override: $descriptor")
     }
 
+    if (!targetClass.hasModifier(KtTokens.IMPL_KEYWORD)) {
+        newMember.removeModifier(KtTokens.IMPL_KEYWORD)
+    }
+
     if (copyDoc) {
         val superDeclaration = DescriptorToSourceUtilsIde.getAnyDeclaration(project, descriptor)?.navigationElement
         val kDoc = when (superDeclaration) {

idea/testData/multiModuleQuickFix/implementMembersInImplClassNonImplInheritor/header/header.kt

@@ -0,0 +1,3 @@
+header abstract class Bar {
+    abstract fun foo()
+}

idea/testData/multiModuleQuickFix/implementMembersInImplClassNonImplInheritor/header/header.kt.after

@@ -0,0 +1,3 @@
+header abstract class Bar {
+    abstract fun foo()
+}

idea/testData/multiModuleQuickFix/implementMembersInImplClassNonImplInheritor/jvm/jvm.kt

@@ -0,0 +1,8 @@
+// "Implement members" "true"
+// DISABLE-ERRORS
+
+abstract impl class Bar {
+    abstract impl fun foo()
+}
+
+class <caret>X : Bar()

idea/testData/multiModuleQuickFix/implementMembersInImplClassNonImplInheritor/jvm/jvm.kt.after

@@ -0,0 +1,12 @@
+// "Implement members" "true"
+// DISABLE-ERRORS
+
+abstract impl class Bar {
+    abstract impl fun foo()
+}
+
+class X : Bar() {
+    override fun foo() {
+        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixMultiModuleTest.kt

@@ -156,4 +156,7 @@ class QuickFixMultiModuleTest : AbstractQuickFixMultiModuleTest() {
 
     @Test
     fun testImplementMembersInHeaderClass() = doMultiPlatformTest(impls = *arrayOf())
+
+    @Test
+    fun testImplementMembersInImplClassNonImplInheritor() = doMultiPlatformTest()
 }