Comment about http 'finish' and (unused) 'prefinish' events.

packages/webapp/webapp_server.js

@@ -218,8 +218,10 @@ WebApp._timeoutAdjustmentRequestCallback = function (req, res) {
   // Insert our new finish listener to run BEFORE the existing one which removes
   // the response from the socket.
   var finishListeners = res.listeners('finish');
-  // XXX Apparently in Node 0.12 this event is now called 'prefinish'.
+  // XXX Apparently in Node 0.12 this event was called 'prefinish'.
   // https://github.com/joyent/node/commit/7c9b6070
+  // But it has switched back to 'finish' in Node v4:
+  // https://github.com/nodejs/node/pull/1411
   res.removeAllListeners('finish');
   res.on('finish', function () {
     res.setTimeout(SHORT_SOCKET_TIMEOUT);