Express addition

node_modules/core-js/modules/_is-integer.js

@@ -0,0 +1,6 @@
+// 20.1.2.3 Number.isInteger(number)
+var isObject = require('./_is-object');
+var floor = Math.floor;
+module.exports = function isInteger(it) {
+  return !isObject(it) && isFinite(it) && floor(it) === it;
+};