stream: fix typo

Also: Revert "stream: Override addListener as well as on"

This reverts commit 18c985919d.

lib/_stream_readable.js

@@ -510,7 +510,7 @@ Readable.prototype.unpipe = function(dest) {
 // kludge for on('data', fn) consumers.  Sad.
 // This is *not* part of the new readable stream interface.
 // It is an ugly unfortunate mess of history.
-Readable.prototype.addListener = Readable.prototype.on = function(ev, fn) {
+Readable.prototype.on = function(ev, fn) {
   var res = Stream.prototype.on.call(this, ev, fn);
 
   // https://github.com/isaacs/readable-stream/issues/16
@@ -549,7 +549,7 @@ function emitDataEvents(stream, startPaused) {
   // convert to an old-style stream.
   stream.readable = true;
   stream.pipe = Stream.prototype.pipe;
-  stream.on = stream.addEventListener = Stream.prototype.on;
+  stream.on = stream.addListener = Stream.prototype.on;
 
   stream.on('readable', function() {
     readable = true;