Remove redundant argument swapping

This conversion occurs inside connection.execute and does not need to be performed here. Doing it here actually breaks passing an options object instead of a query.

Author: Twipped

lib/pool.js

@@ -145,11 +145,6 @@ Pool.prototype.query = function (sql, values, cb) {
 };
 
 Pool.prototype.execute = function (sql, values, cb) {
-  if (typeof values === 'function') {
-    cb = values;
-    values = null;
-  }
-
   var useNamedPlaceholders = this.config.connectionConfig.namedPlaceholders;
 
   this.getConnection(function (err, conn) {