Fix 23563: double unary- operator unstable for NANs

tests/language/nan_identical_test.dart

+// Copyright (c) 2015, 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.
+// Test a new statement by itself.
+// VMOptions=--optimization-counter-threshold=4 --no-use-osr
+
+import "package:expect/expect.dart";
+
+main() {
+  for (int i = 0; i < 100; i++) {
+    Expect.isFalse(checkIdentical(double.NAN, -double.NAN));
+    Expect.isTrue(checkIdentical(double.NAN, double.NAN));
+    Expect.isTrue(checkIdentical(-double.NAN, -double.NAN));

[koda, 2015/06/02 21:20:57]

You should also test the return value for other NaNs.

[srdjan, 2015/06/02 22:32:10]

Done.

+  }
+}
+
+checkIdentical(a, b) => identical(a, b);