Fix windows build.

third_party/fdlibm/fdlibm.cc

 // The following is adapted from fdlibm (http://www.netlib.org/fdlibm).
 //
 // ====================================================
 // Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 //
 // Developed at SunSoft, a Sun Microsystems, Inc. business.
 // Permission to use, copy, modify, and distribute this
 // software is freely granted, provided that this notice
 // is preserved.
 // ====================================================
 //
 // The original source code covered by the above license above has been
 // modified significantly by Google Inc.
 // Copyright 2014 the V8 project authors. All rights reserved.
 
+#include <cmath>
+
 #include "src/v8.h"
 
 #include "src/double.h"
 #include "third_party/fdlibm/fdlibm.h"
 
 
 namespace v8 {
 namespace internal {
 
 const double TrigonometricConstants::constants[] = {
@@ skipping 223 matching lines @@
   int n = __kernel_rem_pio2(tx, y, e0, nx);
   if (hx < 0) {
     y[0] = -y[0];
     y[1] = -y[1];
     return -n;
   }
   return n;
 }
 }
 }  // namespace v8::internal