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/test/collections/ArrayDequeTest.kt

@@ -5,6 +5,7 @@
 
 package test.collections
 
+import test.*
 import test.collections.behaviors.iteratorBehavior
 import test.collections.behaviors.listIteratorBehavior
 import test.collections.behaviors.listIteratorProperties
@@ -622,12 +623,20 @@ class ArrayDequeTest {
 
             val dest = Array(expected.size + 2) { it + 100 }
 
-            @Suppress("UNCHECKED_CAST")
-            val nullTerminatedExpected = (expected as Array<Any?>) + null + (expected.size + 101)
+            val expectedDest = buildList {
+                addAll(expected)
+                if (TestPlatform.current == TestPlatform.Jvm) {
+                    add(null)
+                } else {
+                    add(expected.size + 100)
+                }
+                add(expected.size + 101)
+            }.toTypedArray()
+
             val actual = deque.testToArray(dest)
             assertTrue(
-                nullTerminatedExpected contentEquals actual,
-                message = "Expected: ${nullTerminatedExpected.contentToString()}, Actual: ${actual.contentToString()}"
+                expectedDest contentEquals actual,
+                message = "Expected: ${expectedDest.contentToString()}, Actual: ${actual.contentToString()}"
             )
         }
 

libraries/stdlib/test/collections/CollectionTest.kt

@@ -1311,7 +1311,12 @@ class CollectionTest {
         assertTrue("toArray1" in coll.invocations || "toArray2" in coll.invocations)
 
         val arr2: Array<String> = coll.toArray(Array(coll.size + 1) { "" })
-        assertEquals(data + listOf(null), arr2.asList())
+        testOnlyOn(TestPlatform.Jvm) {
+            assertEquals(data + listOf(null), arr2.asList())
+        }
+        testExceptOn(TestPlatform.Jvm) {
+            assertEquals(data + listOf(""), arr2.asList())
+        }
     }
 
     @Test