--- /dev/null
+var Reflect = require('./_Reflect'),
+ iteratorToArray = require('./_iteratorToArray');
+
+/** Used for built-in method references. */
+var objectProto = Object.prototype;
+
+/** Built-in value references. */
+var enumerate = Reflect ? Reflect.enumerate : undefined,
+ propertyIsEnumerable = objectProto.propertyIsEnumerable;
+
+/**
+ * The base implementation of `_.keysIn` which doesn't skip the constructor
+ * property of prototypes or treat sparse arrays as dense.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @returns {Array} Returns the array of property names.
+ */
+function baseKeysIn(object) {
+ object = object == null ? object : Object(object);
+
+ var result = [];
+ for (var key in object) {
+ result.push(key);
+ }
+ return result;
+}
+
+// Fallback for IE < 9 with es6-shim.
+if (enumerate && !propertyIsEnumerable.call({ 'valueOf': 1 }, 'valueOf')) {
+ baseKeysIn = function(object) {
+ return iteratorToArray(enumerate(object));
+ };
+}
+
+module.exports = baseKeysIn;