old_contents: /**
   * Copyright 2015 The Incremental DOM Authors. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS-IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  /**
   * A cached reference to the hasOwnProperty function.
   */
  const hasOwnProperty = Object.prototype.hasOwnProperty;
  
  
  /**
   * A cached reference to the create function.
   */
  const create = Object.create;
  
  
  /**
   * Used to prevent property collisions between our "map" and its prototype.
   * @param {!Object<string, *>} map The map to check.
   * @param {string} property The property to check.
   * @return {boolean} Whether map has property.
   */
  const has = function(map, property) {
    return hasOwnProperty.call(map, property);
  };
  
  
  /**
   * Creates an map object without a prototype.
   * @return {!Object}
   */
  const createMap = function() {
    return create(null);
  };
  
  
  /** */
  export {
    createMap,
    has
  };
  
  
new_contents: /**
   * Copyright 2015 The Incremental DOM Authors. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS-IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  /**
   * A cached reference to the hasOwnProperty function.
   */
  const hasOwnProperty = Object.prototype.hasOwnProperty;
  
  
  /**
   * A constructor function that will create blank objects.
   * @constructor
   */
  function Blank() {}
  
  Blank.prototype = Object.create(null);
  
  
  /**
   * Used to prevent property collisions between our "map" and its prototype.
   * @param {!Object<string, *>} map The map to check.
   * @param {string} property The property to check.
   * @return {boolean} Whether map has property.
   */
  const has = function(map, property) {
    return hasOwnProperty.call(map, property);
  };
  
  
  /**
   * Creates an map object without a prototype.
   * @return {!Object}
   */
  const createMap = function() {
    return new Blank();
  };
  
  
  /** */
  export {
    createMap,
    has
  };
  
  
subject: Use a faster blank object creator