Fix doc wording around covariance/invariance

libraries/stdlib/js/src/kotlin/collections/AbstractMutableCollection.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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.
  */
 
@@ -8,7 +8,7 @@ package kotlin.collections
 /**
  * Provides a skeletal implementation of the [MutableCollection] interface.
  *
- * @param E the type of elements contained in the collection. The collection is invariant on its element type.
+ * @param E the type of elements contained in the collection. The collection is invariant in its element type.
  */
 public actual abstract class AbstractMutableCollection<E> protected actual constructor() : AbstractCollection<E>(), MutableCollection<E> {
 

libraries/stdlib/js/src/kotlin/collections/AbstractMutableList.kt

@@ -1,7 +1,8 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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.
  */
+
 /*
  * Based on GWT AbstractList
  * Copyright 2007 Google Inc.
@@ -13,7 +14,7 @@ package kotlin.collections
 /**
  * Provides a skeletal implementation of the [MutableList] interface.
  *
- * @param E the type of elements contained in the list. The list is invariant on its element type.
+ * @param E the type of elements contained in the list. The list is invariant in its element type.
  */
 public actual abstract class AbstractMutableList<E> protected actual constructor() : AbstractMutableCollection<E>(), MutableList<E> {
     protected var modCount: Int = 0

libraries/stdlib/js/src/kotlin/collections/AbstractMutableMap.kt

@@ -1,7 +1,8 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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.
  */
+
 /*
  * Based on GWT AbstractMap
  * Copyright 2007 Google Inc.
@@ -14,8 +15,8 @@ package kotlin.collections
  *
  * The implementor is required to implement [entries] property, which should return mutable set of map entries, and [put] function.
  *
- * @param K the type of map keys. The map is invariant on its key type.
- * @param V the type of map values. The map is invariant on its value type.
+ * @param K the type of map keys. The map is invariant in its key type.
+ * @param V the type of map values. The map is invariant in its value type.
  */
 public actual abstract class AbstractMutableMap<K, V> protected actual constructor() : AbstractMap<K, V>(), MutableMap<K, V> {
 

libraries/stdlib/js/src/kotlin/collections/AbstractMutableSet.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 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 kotlin.collections
@@ -7,7 +7,7 @@ package kotlin.collections
 /**
  * Provides a skeletal implementation of the [MutableSet] interface.
  *
- * @param E the type of elements contained in the set. The set is invariant on its element type.
+ * @param E the type of elements contained in the set. The set is invariant in its element type.
  */
 public actual abstract class AbstractMutableSet<E> protected actual constructor() : AbstractMutableCollection<E>(), MutableSet<E> {