Show line markers for sealed classes

#KT-16755 Fixed

idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt

@@ -45,6 +45,7 @@ import org.jetbrains.kotlin.idea.highlighter.allImplementingCompatibleModules
 import org.jetbrains.kotlin.idea.util.ProjectRootsUtil
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.isInheritable
 import org.jetbrains.kotlin.psi.psiUtil.isOverridable
 import java.awt.event.MouseEvent
 import java.util.*
@@ -227,8 +228,7 @@ private fun collectSuperDeclarationMarkers(declaration: KtDeclaration, result: M
 }
 
 private fun collectInheritedClassMarker(element: KtClass, result: MutableCollection<LineMarkerInfo<*>>) {
-    val isTrait = element.isInterface()
-    if (!(isTrait || element.hasModifier(KtTokens.OPEN_KEYWORD) || element.hasModifier(KtTokens.ABSTRACT_KEYWORD))) {
+    if (!element.isInheritable()) {
         return
     }
 
@@ -241,7 +241,7 @@ private fun collectInheritedClassMarker(element: KtClass, result: MutableCollect
     result.add(LineMarkerInfo(
             anchor,
             anchor.textRange,
-            if (isTrait) IMPLEMENTED_MARK else OVERRIDDEN_MARK,
+            if (element.isInterface()) IMPLEMENTED_MARK else OVERRIDDEN_MARK,
             Pass.LINE_MARKERS,
             SUBCLASSED_CLASS.tooltip,
             SUBCLASSED_CLASS.navigationHandler,

idea/testData/codeInsight/lineMarker/overrideImplement/SealedClass.kt

@@ -0,0 +1,9 @@
+sealed class <lineMarker>A</lineMarker> {
+  open fun <lineMarker>a</lineMarker>(){
+  }
+}
+
+class B:A(){
+  override fun <lineMarker>a</lineMarker>(){
+  }
+}

idea/tests/org/jetbrains/kotlin/idea/codeInsight/LineMarkersTestGenerated.java

@@ -182,6 +182,12 @@ public class LineMarkersTestGenerated extends AbstractLineMarkersTest {
             doTest(fileName);
         }
 
+        @TestMetadata("SealedClass.kt")
+        public void testSealedClass() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/lineMarker/overrideImplement/SealedClass.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("ToStringInTrait.kt")
         public void testToStringInTrait() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/codeInsight/lineMarker/overrideImplement/ToStringInTrait.kt");