stylelint-bundle-worker.js
function ( docId, cacheDir ) {
    var obj = Object.create( cache );
    obj.load( docId, cacheDir );
    return obj;
  }
function ( docId, cacheDir ) {
    var obj = Object.create( cache );
    obj.load( docId, cacheDir );
    return obj;
  }
Load a cache identified by the given Id. If the element does not exists, then initialize an empty
cache storage.

@method create
@param docId {String} the id of the cache, would also be used as the name of the file cache
@param [cacheDir] {String} directory for the cache entry
@returns {cache} cache instance