Remove isnan() check in JS_IS_NUM() macro because Win32 doesn't have isnan()

This makes JS_IS_NUM() the same as JS_IS_NUMBER().

src/sbbs3/sbbs.h

@@ -1035,7 +1035,7 @@ extern "C" {
 	DLLEXPORT JSBool	DLLCALL js_CreateArrayOfStrings(JSContext* cx, JSObject* parent
 														,const char* name, char* str[], uintN flags);
 
-	#define JSVAL_IS_NUM(v)		(JSVAL_IS_NUMBER(v) && (!JSVAL_IS_DOUBLE(v) || !isnan(JSVAL_TO_DOUBLE(v))))
+	#define JSVAL_IS_NUM(v)		(JSVAL_IS_NUMBER(v))
 
 	/* js_server.c */
 	DLLEXPORT JSObject* DLLCALL js_CreateServerObject(JSContext* cx, JSObject* parent