Don't define log2 and log2f in blink

third_party/WebKit/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 41 matching lines @@
 
 const double piOverTwoDouble = M_PI_2;
 const float piOverTwoFloat = static_cast<float>(M_PI_2);
 
 const double piOverFourDouble = M_PI_4;
 const float piOverFourFloat = static_cast<float>(M_PI_4);
 
 const double twoPiDouble = piDouble * 2.0;
 const float twoPiFloat = piFloat * 2.0f;
 
-#if OS(ANDROID) || COMPILER(MSVC)
-// ANDROID and MSVC's math.h does not currently supply log2 or log2f.
+#if OS(ANDROID)
+// ANDROID's math.h does not currently supply log2 or log2f.
 inline double log2(double num) {
   // This constant is roughly M_LN2, which is not provided by default on Windows
   // and Android.
   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;
@@ skipping 367 matching lines @@
   if (i >> 2)
     log2 += 2, i >>= 2;
   if (i >> 1)
     log2 += 1;
   return log2;
 }
 
 }  // namespace WTF
 
 #endif  // #ifndef WTF_MathExtras_h