Split int_parse_radix_test into strong and non-strong parts.

tests/corelib/int_parse_radix_bad_handler_test.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "package:expect/expect.dart";
+
+void main() {
+  // If handleError isn't an unary function, and it's called, it also throws
+  // (either TypeError in checked mode, or some failure in unchecked mode).
+
+  // These are compile time errors for strong mode.
+  Expect.throws(() => int.parse("9", radix: 8, onError: "not a function"));
+  Expect.throws(() => int.parse("9", radix: 8, onError: () => 42));
+  Expect.throws(() => int.parse("9", radix: 8, onError: (v1, v2) => 42));
+}