Refactored tests using Array constructor:

Some moved to tests with stdlib
Some changed to use arrayOfNulls

compiler/testData/codegen/box/arrays/iterator.kt

@@ -1,9 +0,0 @@
-fun box(): String {
-    val x = Array<Int>(5, { it } ).iterator()
-    var i = 0
-    while (x.hasNext()) {
-        if (x.next() != i) return "Fail $i"
-        i++
-    }
-    return "OK"
-}