Bump to v4.0.0.

internal/mapClear.js

@@ -0,0 +1,15 @@
+define(['./Hash', './Map'], function(Hash, Map) {
+
+  /**
+   * Removes all key-value entries from the map.
+   *
+   * @private
+   * @name clear
+   * @memberOf MapCache
+   */
+  function mapClear() {
+    this.__data__ = { 'hash': new Hash, 'map': Map ? new Map : [], 'string': new Hash };
+  }
+
+  return mapClear;
+});