win: _set_ouput_format is no longer available or required on VS2015

Source/core/css/CSSPrimitiveValue.cpp

Index: Source/core/css/CSSPrimitiveValue.cpp
diff --git a/Source/core/css/CSSPrimitiveValue.cpp b/Source/core/css/CSSPrimitiveValue.cpp
index 0fc04f0ad270edc9d6df18fa4a22119fd402f35d..048fe6d3becb34af491cb7f2ecf579b56cf3e90b 100644
--- a/Source/core/css/CSSPrimitiveValue.cpp
+++ b/Source/core/css/CSSPrimitiveValue.cpp
@@ -826,11 +826,11 @@ String CSSPrimitiveValue::getStringValue() const
 
 static String formatNumber(double number, const char* suffix, unsigned suffixLength)
 {
-#if OS(WIN)
+#if OS(WIN) && _MSC_VER < 1900
     unsigned oldFormat = _set_output_format(_TWO_DIGIT_EXPONENT);
 #endif
     String result = String::format("%.6g", number);
-#if OS(WIN)
+#if OS(WIN) && _MSC_VER < 1900
     _set_output_format(oldFormat);
 #endif
     result.append(suffix, suffixLength);