Check for negative zero in floor when compiling with MSVC.

src/utils.h

Index: src/utils.h
diff --git a/src/utils.h b/src/utils.h
index 7831fa9fee6e14778f467c74498784b0c2f57e7b..d7967e7f0e20a49c4768ce9cedff3c5e9ad65581 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -8,6 +8,7 @@
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
+#include <cmath>
 
 #include "include/v8.h"
 #include "src/allocation.h"
@@ -140,6 +141,15 @@ T Abs(T a) {
 }
 
 
+// Floor(-0.0) == 0.0
+inline double Floor(double x) {
+#ifdef _MSC_VER
+  if (x == 0) return x;  // Fix for issue 3477.
+#endif
+  return std::floor(x);
+}
+
+
 // TODO(svenpanne) Clean up the whole power-of-2 mess.
 inline int32_t WhichPowerOf2Abs(int32_t x) {
   return (x == kMinInt) ? 31 : WhichPowerOf2(Abs(x));