Replace our home-grown BitCast with bit_cast from Chrome/Google3.

src/conversions-inl.h

 // Copyright 2011 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_CONVERSIONS_INL_H_
 #define V8_CONVERSIONS_INL_H_
 
 #include <float.h>         // Required for DBL_MAX and on Win32 for finite()
 #include <limits.h>        // Required for INT_MAX etc.
 #include <stdarg.h>
 #include <cmath>
 #include "src/globals.h"       // Required for V8_INFINITY
 
 // ----------------------------------------------------------------------------
 // Extra POSIX/ANSI functions for Win32/MSVC.
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/conversions.h"
 #include "src/double.h"
 #include "src/scanner.h"
 #include "src/strtod.h"
 
 namespace v8 {
 namespace internal {
 
 inline double JunkStringValue() {
-  return BitCast<double, uint64_t>(kQuietNaNMask);
+  return bit_cast<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
@@ skipping 638 matching lines @@
   SLOW_DCHECK(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_