Method sepatators: show separator between companion object and function

#KT-24352 Fixed

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

@@ -65,7 +65,10 @@ class KotlinLineMarkerProvider : LineMarkerProviderDescriptor() {
     }
 
     private fun PsiElement?.canHaveSeparator() =
-        this is KtFunction || this is KtClassInitializer || (this is KtProperty && !isLocal)
+        this is KtFunction
+                || this is KtClassInitializer
+                || (this is KtProperty && !isLocal)
+                || ((this is KtObjectDeclaration && this.isCompanion()))
 
     private fun PsiElement.wantsSeparator() = this is KtFunction || StringUtil.getLineBreakCount(text) > 0
 

idea/testData/codeInsight/lineMarker/MethodSeparators.kt

@@ -39,4 +39,8 @@ class Foo {
     <lineMarker descr="null">fun</lineMarker> f1() = 1
 
     <lineMarker descr="null">fun</lineMarker> f2() = 2
+
+    <lineMarker descr="null">companion</lineMarker> object {
+        const val C = 1
+    }
 }