Bump to v4.12.0.

_listCacheHas.js

@@ -0,0 +1,17 @@
+define(['./_assocIndexOf'], function(assocIndexOf) {
+
+  /**
+   * Checks if a list cache value for `key` exists.
+   *
+   * @private
+   * @name has
+   * @memberOf ListCache
+   * @param {string} key The key of the entry to check.
+   * @returns {boolean} Returns `true` if an entry for `key` exists, else `false`.
+   */
+  function listCacheHas(key) {
+    return assocIndexOf(this.__data__, key) > -1;
+  }
+
+  return listCacheHas;
+});