Actually fix build.

src/conversions-inl.h

 // Copyright 2011 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 33 matching lines @@
 #include "strtod.h"
 
 namespace v8 {
 namespace internal {
 
 inline double JunkStringValue() {
   return BitCast<double, uint64_t>(kQuietNaNMask);
 }
 
 
+inline double SignedZero(bool negative) {
+  return negative ? uint64_to_double(Double::kSignMask) : 0.0;
+}
+
+
 // The fast double-to-unsigned-int conversion routine does not guarantee
 // rounding towards zero, or any reasonable value if the argument is larger
 // than what fits in an unsigned 32-bit integer.
 inline unsigned int FastD2UI(double x) {
   // There is no unsigned version of lrint, so there is no fast path
   // in this function as there is in FastD2I. Using lrint doesn't work
   // for values of 2^31 and above.
 
   // Convert "small enough" doubles to uint32_t by fixing the 32
   // least significant non-fractional bits in the low 32 bits of the
@@ skipping 602 matching lines @@
   ASSERT(buffer_pos < kBufferSize);
   buffer[buffer_pos] = '\0';
 
   double converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
   return (sign == NEGATIVE) ? -converted : converted;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONVERSIONS_INL_H_