Reinstate workarounds for atan2, fmod, pow in MathExtras on vs2013

Source/wtf/MathExtras.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 98 matching lines @@
     return log(num) / 0.693147180559945309417232121458176568;
 }
 
 inline float log2f(float num)
 {
     // This constant is roughly M_LN2, which is not provided by default on Windows and Android.
     return logf(num) / 0.693147180559945309417232121458176568f;
 }
 #endif
 
-#if COMPILER(MSVC) && (_MSC_VER < 1800)
+#if COMPILER(MSVC)
+
+// VS2013 has most of the math functions now, but we still need to work
+// around various differences in behavior of Inf.
+
+#if _MSC_VER < 1800
 
 namespace std {
 
 inline bool isinf(double num) { return !_finite(num) && !_isnan(num); }
 inline bool isnan(double num) { return !!_isnan(num); }
 inline bool isfinite(double x) { return _finite(x); }
 inline bool signbit(double num) { return _copysign(1.0, num) < 0; }
 
 } // namespace std
 
 inline double nextafter(double x, double y) { return _nextafter(x, y); }
 inline float nextafterf(float x, float y) { return x > y ? x - FLT_EPSILON : x + FLT_EPSILON; }
 
 inline double copysign(double x, double y) { return _copysign(x, y); }
 
+#endif // _MSC_VER
+
 // Work around a bug in Win, where atan2(+-infinity, +-infinity) yields NaN instead of specific values.
 inline double wtf_atan2(double x, double y)
 {
     double posInf = std::numeric_limits<double>::infinity();
     double negInf = -std::numeric_limits<double>::infinity();
     double nan = std::numeric_limits<double>::quiet_NaN();
 
     double result = nan;
 
     if (x == posInf && y == posInf)
@@ skipping 13 matching lines @@
 // Work around a bug in the Microsoft CRT, where fmod(x, +-infinity) yields NaN instead of x.
 inline double wtf_fmod(double x, double y) { return (!std::isinf(x) && std::isinf(y)) ? x : fmod(x, y); }
 
 // Work around a bug in the Microsoft CRT, where pow(NaN, 0) yields NaN instead of 1.
 inline double wtf_pow(double x, double y) { return y == 0 ? 1 : pow(x, y); }
 
 #define atan2(x, y) wtf_atan2(x, y)
 #define fmod(x, y) wtf_fmod(x, y)
 #define pow(x, y) wtf_pow(x, y)
 
+#if _MSC_VER < 1800
+
 // MSVC's math functions do not bring lrint.
 inline long int lrint(double flt)
 {
     int64_t intgr;
 #if CPU(X86)
     __asm {
         fld flt
         fistp intgr
     };
 #else
     ASSERT(std::isfinite(flt));
     double rounded = round(flt);
     intgr = static_cast<int64_t>(rounded);
     // If the fractional part is exactly 0.5, we need to check whether
     // the rounded result is even. If it is not we need to add 1 to
     // negative values and subtract one from positive values.
     if ((fabs(intgr - flt) == 0.5) & intgr)
         intgr -= ((intgr >> 62) | 1); // 1 with the sign of result, i.e. -1 or 1.
 #endif
     return static_cast<long int>(intgr);
 }
 
+#endif // _MSC_VER
+
 #endif // COMPILER(MSVC)
 
 inline double deg2rad(double d)  { return d * piDouble / 180.0; }
 inline double rad2deg(double r)  { return r * 180.0 / piDouble; }
 inline double deg2grad(double d) { return d * 400.0 / 360.0; }
 inline double grad2deg(double g) { return g * 360.0 / 400.0; }
 inline double turn2deg(double t) { return t * 360.0; }
 inline double deg2turn(double d) { return d / 360.0; }
 inline double rad2grad(double r) { return r * 200.0 / piDouble; }
 inline double grad2rad(double g) { return g * piDouble / 200.0; }
@@ skipping 109 matching lines @@
     if (i >> 2)
         log2 += 2, i >>= 2;
     if (i >> 1)
         log2 += 1;
     return log2;
 }
 
 } // namespace WTF
 
 #endif // #ifndef WTF_MathExtras_h