Fix Double.NextDouble function.

src/double.h

 // Copyright 2010 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 65 matching lines @@
     e -= DiyFp::kSignificandSize - kSignificandSize;
     return DiyFp(f, e);
   }
 
   // Returns the double's bit as uint64.
   uint64_t AsUint64() const {
     return d64_;
   }
 
   double NextDouble() const {
-    if (d64_ == kInfinity) return kInfinity;
-    return Double(d64_ + 1).value();
+    if (d64_ == kInfinity) return Double(kInfinity).value();
+    if (Sign() < 0 && Significand() == 0) {
+      // -0.0
+      return 0.0;
+    }
+    if (Sign() < 0) {
+      return Double(d64_ - 1).value();
+    } else {
+      return Double(d64_ + 1).value();
+    }
   }
 
   int Exponent() const {
     if (IsDenormal()) return kDenormalExponent;
 
     uint64_t d64 = AsUint64();
     int biased_e =
         static_cast<int>((d64 & kExponentMask) >> kPhysicalSignificandSize);
     return biased_e - kExponentBias;
   }
@@ skipping 115 matching lines @@
       biased_exponent = static_cast<uint64_t>(exponent + kExponentBias);
     }
     return (significand & kSignificandMask) |
         (biased_exponent << kPhysicalSignificandSize);
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_DOUBLE_H_