Fix for KT-12582: "VerifyError: Bad local variable type" caused by explicit loop variable type

#KT-12582 Fixed

compiler/testData/codegen/box/ranges/nullableLoopParameter/progressionExpression.kt

@@ -0,0 +1,12 @@
+fun box(): String {
+    var result = 0
+    val intRange: IntProgression = 1..3
+    for (i: Int? in intRange) {
+        result = sum(result, i)
+    }
+    return if (result == 6) "OK" else "fail: $result"
+}
+
+fun sum(i: Int, z: Int?): Int {
+    return i + z!!
+}