Bump to v4.0.0.

internal/createSet.js

@@ -0,0 +1,15 @@
+define(['./Set', '../noop'], function(Set, noop) {
+
+  /**
+   * Creates a set of `values`.
+   *
+   * @private
+   * @param {Array} values The values to add to the set.
+   * @returns {Object} Returns the new set.
+   */
+  var createSet = !(Set && new Set([1, 2]).size === 2) ? noop : function(values) {
+    return new Set(values);
+  };
+
+  return createSet;
+});