Bump to v4.0.0.

internal/baseHas.js

@@ -0,0 +1,26 @@
+/** Used for built-in method references. */
+var objectProto = Object.prototype;
+
+/** Used to check objects for own properties. */
+var hasOwnProperty = objectProto.hasOwnProperty;
+
+/** Built-in value references. */
+var getPrototypeOf = Object.getPrototypeOf;
+
+/**
+ * The base implementation of `_.has` without support for deep paths.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @param {Array|string} key The key to check.
+ * @returns {boolean} Returns `true` if `key` exists, else `false`.
+ */
+function baseHas(object, key) {
+  // Avoid a bug in IE 10-11 where objects with a [[Prototype]] of `null`,
+  // that are composed entirely of index properties, return `false` for
+  // `hasOwnProperty` checks of them.
+  return hasOwnProperty.call(object, key) ||
+    (typeof object == 'object' && key in object && getPrototypeOf(object) === null);
+}
+
+export default baseHas;