src: remove unused function

The function IsInt64() in src/node_file.cc is no longer used.
This commit removes it.

PR-URL: nodejs#17671
Reviewed-By: Timothy Gu <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Rich Trott <[email protected]>
Reviewed-By: Daniel Bevenius <[email protected]>
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Evan Lucas <[email protected]>
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Jon Moss <[email protected]>

Author: cjihrig

src/node_file.cc

@@ -154,10 +154,6 @@ void NewFSReqWrap(const FunctionCallbackInfo<Value>& args) {
 }
 
 
-inline bool IsInt64(double x) {
-  return x == static_cast<double>(static_cast<int64_t>(x));
-}
-
 void After(uv_fs_t *req) {
   FSReqWrap* req_wrap = static_cast<FSReqWrap*>(req->data);
   CHECK_EQ(req_wrap->req(), req);