Remove windows/mac/ios specific code from //ui

ui/gfx/animation/tween_unittest.cc

Index: ui/gfx/animation/tween_unittest.cc
diff --git a/ui/gfx/animation/tween_unittest.cc b/ui/gfx/animation/tween_unittest.cc
index f71a77dccbdd7bf480dce2fe8bbc318c16d71a1c..187d9497ff7868cfb2bd44c46053746b56991fa7 100644
--- a/ui/gfx/animation/tween_unittest.cc
+++ b/ui/gfx/animation/tween_unittest.cc
@@ -6,10 +6,6 @@
 
 #include <math.h>
 
-#if defined(OS_WIN)
-#include <float.h>
-#endif
-
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/test/gfx_util.h"
 
@@ -17,14 +13,10 @@ namespace gfx {
 namespace {
 
 double next_double(double d) {
-#if defined(OS_WIN)
-  return _nextafter(d, d + 1);
-#else
   // Step two units of least precision towards positive infinity. On some 32
   // bit x86 compilers a single step was not enough due to loss of precision in
   // optimized code.
   return nextafter(nextafter(d, d + 1), d + 1);
-#endif
 }
 
 // Validates that the same interpolations are made as in Blink.