- implement IsNegative for class Double

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 <math.h>
 
 #include "vm/bootstrap_natives.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/code_generator.h"  // DartModulo.
@@ skipping 253 matching lines @@
 
 DEFINE_NATIVE_ENTRY(Double_getIsNaN, 1) {
   const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
   return Bool::Get(isnan(arg.value())).raw();
 }
 
 
 DEFINE_NATIVE_ENTRY(Double_getIsNegative, 1) {
   const Double& arg = Double::CheckedHandle(arguments->NativeArgAt(0));
   // Include negative zero, infinity.
-  return Bool::Get(signbit(arg.value()) && !isnan(arg.value())).raw();
+  return Bool::Get(arg.IsNegative()).raw();
 }
 
 // Add here only functions using/referring to old-style casts.
 
 }  // namespace dart