Implement proposed new identity spec.

tests/language/number_identity_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 program for testing params.
+
+main() {
+  for (int i = 0; i < 1000; i++) testNumberIdentity();
+}
+
+
+testNumberIdentity () {
+  var a = 1.0;
+  var b = a + 0.0;
+  Expect.isTrue(identical(a, b));
+  a = double.NAN;
+  b = a + 0.0;
+  // Expect.isTrue(identical(a, b));  // Fails on dart2js, clarify.
+  a = 2210713829375;
+  b = a + 0;
+  Expect.isTrue(identical(a, b));
+  a = 22107138293752210713829375;
+  b = a + 0;
+  Expect.isTrue(identical(a, b));
+  b = a + 1;
+  // Expect.isFalse(identical(a, b));  // Fails on dart2js, since bigint.

[Florian Schneider, 2012/11/23 10:33:40]

Maybe group the tests where dart2js currently differs from the VM in a separate
file, so that we can mark just those in the test expectations file.

[srdjan, 2012/11/23 19:45:39]

Added two test files:
- one is for NaN, where we would expect dart2js to pass
- one is for working with bigints which is not supportable with dart2js


Also added appropriate status files changes and added more combined tests, using
mint value that is mint in x64 as well.

+}