Add operator modifier by inspection on idea module

idea/jvm-debugger/jvm-debugger-core/src/org/jetbrains/kotlin/idea/debugger/stepping/KotlinSteppingCommandProvider.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.idea.debugger.stepping
@@ -177,7 +166,7 @@ class KotlinSteppingCommandProvider : JvmSteppingCommandProvider() {
     }
 }
 
-private fun PsiElement?.contains(element: PsiElement): Boolean {
+private operator fun PsiElement?.contains(element: PsiElement): Boolean {
     return this?.textRange?.contains(element.textRange) ?: false
 }