Fix language test that failed on mips hardware, because the created NaN happened

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-background-compilation
 
 import 'dart:typed_data';
 
 import "package:expect/expect.dart";
 
-double uint64toDouble(int i) {
+double createOtherNAN() {
   var buffer = new Uint8List(8).buffer;
   var bdata = new ByteData.view(buffer);
-  bdata.setUint64(0, i);
-  return bdata.getFloat64(0);
-}
-
-double createOtherNAN() {
-  return uint64toDouble((1 << 64) - 2);
+  bdata.setFloat64(0, double.NAN);
+  bdata.setInt8(7, bdata.getInt8(7) ^ 1);  // Flip bit 0, big endian.
+  double result = bdata.getFloat64(0);
+  Expect.isTrue(result.isNaN);
+  return result;
 }
 
 main() {
   var otherNAN = createOtherNAN();
   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));
 
     Expect.isFalse(checkIdentical(otherNAN, -otherNAN));
@@ skipping 12 matching lines @@
     Expect.isFalse(checkIdentical(-a, -b));
     Expect.isFalse(checkIdentical(-a, b));
     Expect.isFalse(checkIdentical(a, -b));
 
     Expect.isTrue(checkIdentical(-(-a), a));
     Expect.isTrue(checkIdentical(-(-b), b));
   }
 }
 
 checkIdentical(a, b) => identical(a, b);