Change Expect.identical(NaN, x) to not assume NaNs are identical.

tests/lib/math/double_pow_test.dart

 // Copyright (c) 2011, 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.
 
 library math_test;
 import "package:expect/expect.dart";
 import 'dart:math';
 
 void checkVeryClose(double a, double b) {
   // We find a ulp (unit in the last place) by shifting the original number
@@ skipping 48 matching lines @@
     // if `y` is zero (0.0 or -0.0), the result is always 1.0.
     Expect.identical(1.0, pow(d, 0.0), "$d");
     Expect.identical(1.0, pow(d, -0.0), "$d");
   }
   for (var d in samples) {
     // if `x` is 1.0, the result is always 1.0.
     Expect.identical(1.0, pow(1.0, d), "$d");
   }
   for (var d in samples) {
     // otherwise, if either `x` or `y` is NaN then the result is NaN.
-    if (d != 0.0) Expect.identical(NaN, pow(NaN, d), "$d");
-    if (d != 1.0) Expect.identical(NaN, pow(d, NaN), "$d");
+    if (d != 0.0) Expect.isTrue(pow(NaN, d).isNaN, "$d");
+    if (d != 1.0) Expect.isTrue(pow(d, NaN).isNaN, "$d");
   }
 
   for (var d in samples) {
     // if `x` is a finite and strictly negative and `y` is a finite non-integer,
     // the result is NaN.
     if (d < 0 && !d.isInfinite) {
-      Expect.identical(NaN, pow(d, 0.5), "$d");
-      Expect.identical(NaN, pow(d, -0.5), "$d");
-      Expect.identical(NaN, pow(d, 1.5), "$d");
-      Expect.identical(NaN, pow(d, -1.5), "$d");
+      Expect.isTrue(pow(d, 0.5).isNaN, "$d");
+      Expect.isTrue(pow(d, -0.5).isNaN, "$d");
+      Expect.isTrue(pow(d, 1.5).isNaN, "$d");
+      Expect.isTrue(pow(d, -1.5).isNaN, "$d");
     }
   }
 
   for (var d in samples) {
     if (d < 0) {
       // if `x` is Infinity and `y` is strictly negative, the result is 0.0.
       Expect.identical(0.0, pow(Infinity, d), "$d");
     }
     if (d > 0) {
       // if `x` is Infinity and `y` is strictly positive, the result is Infinity.
@@ skipping 58 matching lines @@
   // Underflow.
   Expect.identical(0.0, pow(10.0, -325.0));
 
   // Conversion to double.
 
   // The second argument is an odd integer as int, but not when converted
   // to double.
   Expect.identical(Infinity, pow(-0.0, -9223372036854775809));
 }