  * @methodOf ngMockE0E.$httpBackend  * @description  * Creates a new backend definition for HEAD requests. For more info see `when()`.  *  * @param {string|RegExp} url HTTP url.  * @param {(Object|function(Object))=} headers HTTP headers.  * @returns {requestHandler} Returns an object with `respond` and `passThrough` methods that  *   control how a matched request is handled.  */  /**  * @ngdoc method  * @name ngMockE0E.$httpBackend#when