A64: Fix a few simulation inaccuracies.

src/a64/instructions-a64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 49 matching lines @@
 
 // This value is a signalling NaN as both a double and as a float (taking the
 // least-significant word).
 DEFINE_DOUBLE(kFP64SignallingNaN, 0x7ff000007f800001);
 DEFINE_FLOAT(kFP32SignallingNaN, 0x7f800001);
 
 // A similar value, but as a quiet NaN.
 DEFINE_DOUBLE(kFP64QuietNaN, 0x7ff800007fc00001);
 DEFINE_FLOAT(kFP32QuietNaN, 0x7fc00001);
 
+// The default NaN values (for FPCR.DN=1).
+DEFINE_DOUBLE(kFP64DefaultNaN, 0x7ff8000000000000UL);
+DEFINE_FLOAT(kFP32DefaultNaN, 0x7fc00000);
+
 #undef DEFINE_FLOAT
 #undef DEFINE_DOUBLE
 
 
 enum LSDataSize {
   LSByte        = 0,
   LSHalfword    = 1,
   LSWord        = 2,
   LSDoubleWord  = 3
 };
@@ skipping 427 matching lines @@
   TRACE_ENABLE   = 1 << 6,
   TRACE_DISABLE  = 2 << 6,
   TRACE_OVERRIDE = 3 << 6
 };
 
 
 } }  // namespace v8::internal
 
 
 #endif  // V8_A64_INSTRUCTIONS_A64_H_