Fix a test to not expect NaNs to be bitwise identical.

tests/lib/math/double_pow_test.dart

Index: tests/lib/math/double_pow_test.dart
diff --git a/tests/lib/math/double_pow_test.dart b/tests/lib/math/double_pow_test.dart
index 83a8ecea99790e814503af74d9b5ebad74bf029e..b6fc4b4c095fdc45f9ce05989015ebf57e4b207b 100644
--- a/tests/lib/math/double_pow_test.dart
+++ b/tests/lib/math/double_pow_test.dart
@@ -117,8 +117,8 @@ test() {
     }
     // if `x` is -Infinity or -0.0 and `y` is not an odd integer, then the
     // result is the same as `pow(-x , y)`.
-    Expect.identical(pow(Infinity, d), pow(-Infinity, d));
-    Expect.identical(pow(0.0, d), pow(-0.0, d));
+    Expect.equals(pow(Infinity, d), pow(-Infinity, d));
+    Expect.equals(pow(0.0, d), pow(-0.0, d));

[Lasse Reichstein Nielsen, 2016/08/12 23:52:38]

I'm not sure that's what we want.

If the problem is with different payload NaNs not being identical, then they are
probably not equal either (since NaN isn't even equal to itself).

According to https://api.dartlang.org/stable/1.18.1/dart-math/pow.html, we only
get NaN for a NaN input or pow(finite-negative, non-integer) so these tests
shouldn't be affected at all.

[Florian Schneider, 2016/08/13 00:01:29]

Never mind my first attempt: Can't use == on NaN in any case.

I can only check that both sides are NaN or not, but I don't want to rely on a
specific bit pattern.

   }
 
   for (var d in samples) {
@@ -136,7 +136,7 @@ test() {
       Expect.identical(1.0, pow(d, Infinity));
     }
     // if `y` is -Infinity, the result is `1/pow(x, Infinity)`.
-    Expect.identical(1/pow(d, Infinity), pow(d, -Infinity));
+    Expect.equals(1/pow(d, Infinity), pow(d, -Infinity));

[Lasse Reichstein Nielsen, 2016/08/12 23:52:38]

Again, this should hold, and if it doesn't because of different payload NaNs,
equals shouldn't work either.

   }
 
   // Some non-exceptional values.
@@ -159,4 +159,4 @@ test() {
 
 main() {
   for (int i = 0; i < 10; i++) test();
-}
+}