Refactored tests using Array constructor:

Some moved to tests with stdlib
Some changed to use arrayOfNulls

compiler/testData/codegen/box/controlStructures/forIntArray.kt

@@ -1,11 +1,11 @@
 fun box() : String {
-    val a = Array<Int> (5, {0})
+    val a = arrayOfNulls<Int>(5)
     var i = 0
     var sum = 0
     for(el in 0..4) {
        a[i] = i++
     }
-    for (el in a) {
+    for (el in (a as Array<Int>)) {
         sum = sum + el
     }
     if(sum != 10) return "a failed"