code: function IDBTransaction(db, storeNames, mode) {
          this.__id = ++uniqueID; // for debugging simultaneous transactions
          this.__active = true;
          this.__running = false;
          this.__errored = false;
          this.__requests = [];
          this.__storeNames = storeNames;
          this.mode = mode;
          this.db = db;
          this.error = null;
          this.onabort = this.onerror = this.oncomplete = null;
  
          // Kick off the transaction as soon as all synchronous code is done.
          var me = this;
          setTimeout(function() { me.__executeRequests(); }, 0);
      }
docs: The IndexedDB Transaction
  http://dvcs.w3.org/hg/IndexedDB/raw-file/tip/Overview.html#idl-def-IDBTransaction
  @param {IDBDatabase} db
  @param {string[]} storeNames
  @param {string} mode
  @constructor