Null-terminate Collection.toArray destination only in JVM

In other platforms the elements following the collection elements
should not be changed.

As a part of efforts to stabilize Native stdlib.

libraries/stdlib/native-wasm/src/kotlin/collections/ArrayList.kt

@@ -221,11 +221,7 @@ actual class ArrayList<E> private constructor(
 
         (backingArray as Array<T>).copyInto(array, 0, startIndex = offset, endIndex = offset + length)
 
-        if (array.size > length) {
-            array[length] = null as T // null-terminate
-        }
-
-        return array
+        return terminateCollectionToArray(length, array)
     }
 
     override fun toArray(): Array<Any?> {

libraries/stdlib/native-wasm/src/kotlin/collections/Arrays.kt

@@ -93,6 +93,8 @@ internal actual fun copyToArrayImpl(collection: Collection<*>): Array<Any?> {
     return array
 }
 
+internal actual fun <T> terminateCollectionToArray(collectionSize: Int, array: Array<T>): Array<T> = array
+
 /**
  * Returns a new array which is a copy of the original array with new elements filled with null values.
  */