比较nsIHttpChannel对象，如 HttpFox 的确如此：

Compare nsIHttpChannel objects, like HttpFox does:

getPendingRequestForRequestEvent: function(request) {
   // check for matching request
   for (var i = 0; i < this.Requests.length; i++) {
      if (request.HttpChannel === this.Requests[i].HttpChannel) {
         return i;
      }
   }

   // no match found
   return -1;
},