src: IsInt64() should return bool, not int

src/node_file.cc

@@ -75,7 +75,7 @@ static Persistent<String> oncomplete_sym;
 #define GET_OFFSET(a) ((a)->IsNumber() ? (a)->IntegerValue() : -1)
 #define GET_TRUNCATE_LENGTH(a) ((a)->IntegerValue())
 
-static inline int IsInt64(double x) {
+static inline bool IsInt64(double x) {
   return x == static_cast<double>(static_cast<int64_t>(x));
 }