Bump to v4.0.0.

internal/mapDelete.js

@@ -1,16 +1,20 @@
-define([], function() {
+define(['./Map', './assocDelete', './hashDelete', './isKeyable'], function(Map, assocDelete, hashDelete, isKeyable) {
 
   /**
-   * Removes `key` and its value from the cache.
+   * Removes `key` and its value from the map.
    *
    * @private
    * @name delete
-   * @memberOf _.memoize.Cache
+   * @memberOf MapCache
    * @param {string} key The key of the value to remove.
-   * @returns {boolean} Returns `true` if the entry was removed successfully, else `false`.
+   * @returns {boolean} Returns `true` if the entry was removed, else `false`.
    */
   function mapDelete(key) {
-    return this.has(key) && delete this.__data__[key];
+    var data = this.__data__;
+    if (isKeyable(key)) {
+      return hashDelete(typeof key == 'string' ? data.string : data.hash, key);
+    }
+    return Map ? data.map['delete'](key) : assocDelete(data.map, key);
   }
 
   return mapDelete;