Apply even more let/const transforms.

_listCacheDelete.js

@@ -1,10 +1,10 @@
 import assocIndexOf from './_assocIndexOf.js';
 
 /** Used for built-in method references. */
-var arrayProto = Array.prototype;
+const arrayProto = Array.prototype;
 
 /** Built-in value references. */
-var splice = arrayProto.splice;
+const splice = arrayProto.splice;
 
 /**
  * Removes `key` and its value from the list cache.
@@ -16,13 +16,13 @@ var splice = arrayProto.splice;
  * @returns {boolean} Returns `true` if the entry was removed, else `false`.
  */
 function listCacheDelete(key) {
-  var data = this.__data__,
-      index = assocIndexOf(data, key);
+  const data = this.__data__;
+  const index = assocIndexOf(data, key);
 
   if (index < 0) {
     return false;
   }
-  var lastIndex = data.length - 1;
+  const lastIndex = data.length - 1;
   if (index == lastIndex) {
     data.pop();
   } else {