Fix fix

runtime/lib/double.cc

 // 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.
 
 #include "vm/bootstrap_natives.h"
 
 #include "platform/math.h"
 
 #include "vm/code_generator.h"  // DartModulo.
 #include "vm/dart_entry.h"
@@ skipping 286 matching lines @@
   const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
   // Include negative zero, infinity.
   double dval = arg.value();
   return Bool::Get(signbit(dval) && !isnan(dval)).raw();
 }
 
 
 DEFINE_NATIVE_ENTRY(Double_flipSignBit, 1) {
   const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
   const double in_val = arg.value();
-  // TODO(srdjan): Fix this compilation error.
-  // const int64_t bits =
-  //     *(reinterpret_cast<const int64_t*>(&in_val)) ^ kSignBitDouble;
-  // const double out_val = *(reinterpret_cast<const double*>(&bits));
-  // return Double::New(out_val);
-  return Double::New(-in_val);
+  const int64_t bits = bit_cast<int64_t, double>(in_val) ^ kSignBitDouble;
+  return Double::New(bit_cast<double, int64_t>(bits));
 }
 
 // Add here only functions using/referring to old-style casts.
 
 }  // namespace dart