Fix math min/max for -0.0 case. Enable min_max_test to run in optimizing compiler as well.

tests/lib/math/min_max_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.
 // Dart test for testing Math.min and Math.max.
+// VMOptions=--optimization-counter-threshold=10
 
 library min_max_test;
 import "package:expect/expect.dart";
 import 'dart:math';
 
 testMin() {
   Expect.equals(0, min(0, 2));
   Expect.equals(0, min(2, 0));
 
   Expect.equals(-10, min(-10, -9));
@@ skipping 499 matching lines @@
   Expect.isFalse(max(-inf, 0.0).isNegative);
   Expect.isFalse(max(-inf, 0).isNegative);
   Expect.isTrue(max(-inf, -0.0).isNegative);
   Expect.isTrue(max(-inf, -499).isNegative);
   Expect.isTrue(max(-inf, -499.0).isNegative);
   Expect.isTrue(max(-inf, -inf).isNegative);
 }
 
 main() {
   testMin();
+  testMin();
+  testMax();
   testMax();
 }