Make v8 compile on VS2013.

src/win32-math.cc

 // 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
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 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Extra POSIX/ANSI routines for Win32 when using Visual Studio C++. Please
 // refer to The Open Group Base Specification for specification of the correct
 // semantics for these functions.
 // (http://www.opengroup.org/onlinepubs/000095399/)
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && (_MSC_VER < 1800)
 
 #include "win32-headers.h"
 #include <limits.h>        // Required for INT_MAX etc.
 #include <float.h>         // Required for DBL_MAX and on Win32 for finite()
 #include <cmath>
 #include "win32-math.h"
 
 #include "checks.h"
 
 
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   // and negative versions of zero.
   if (x == 0)
     return _fpclass(x) & _FPCLASS_NZ;
   else
     return x < 0;
 }
 
 }  // namespace std
 
 #endif  // _MSC_VER