Use signaling NaN for holes in fixed double arrays.

src/objects.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/allocation.h"
@@ skipping 2534 matching lines @@
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(FixedArray);
 };
 
 
 // FixedDoubleArray describes fixed-sized arrays with element type double.
 class FixedDoubleArray: public FixedArrayBase {
  public:
   // Setter and getter for elements.
   inline double get_scalar(int index);
-  inline int64_t get_representation(int index);
+  inline uint64_t get_representation(int index);
   static inline Handle<Object> get(Handle<FixedDoubleArray> array, int index);
   inline void set(int index, double value);
   inline void set_the_hole(int index);
 
   // Checking for the hole.
   inline bool is_the_hole(int index);
 
   // Garbage collection support.
   inline static int SizeFor(int length) {
     return kHeaderSize + length * kDoubleSize;
   }
 
   // Gives access to raw memory which stores the array's data.
   inline double* data_start();
 
   inline void FillWithHoles(int from, int to);
 
   // Code Generation support.
   static int OffsetOfElementAt(int index) { return SizeFor(index); }
 
-  inline static bool is_the_hole_nan(double value);
-  inline static double hole_nan_as_double();
-  inline static double canonical_not_the_hole_nan_as_double();
-
   DECLARE_CAST(FixedDoubleArray)
 
   // Maximal allowed size, in bytes, of a single FixedDoubleArray.
   // Prevents overflowing size computations, as well as extreme memory
   // consumption.
   static const int kMaxSize = 512 * MB;
   // Maximally allowed length of a FixedArray.
   static const int kMaxLength = (kMaxSize - kHeaderSize) / kDoubleSize;
 
   // Dispatched behavior.
@@ skipping 8324 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_