readline: clean up event listener in onNewListener

Once the Readline interface is closed, the 'data' event listener should
be removed.

PR-URL: https://github.com/nodejs/node/pull/13266
Ref: https://github.com/nodejs/node/pull/9447#discussion_r86599214
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/readline.js

@@ -1039,6 +1039,9 @@ function emitKeypressEvents(stream, iface) {
   } else {
     stream.on('newListener', onNewListener);
   }
+  if (iface) {
+    iface.once('close', () => { stream.removeListener('data', onData); });
+  }
 }
 
 /**

test/parallel/test-readline-set-raw-mode.js

@@ -74,6 +74,8 @@ assert(!rawModeCalled);
 assert(resumeCalled);
 assert(!pauseCalled);
 
+// One data listener for the keypress events.
+assert.strictEqual(stream.listeners('data').length, 1);
 
 // close() should call setRawMode(false)
 expectedRawMode = false;
@@ -86,5 +88,5 @@ assert(!resumeCalled);
 assert(pauseCalled);
 
 assert.deepStrictEqual(stream.listeners('keypress'), []);
-// one data listener for the keypress events.
-assert.strictEqual(stream.listeners('data').length, 1);
+// Data listener is removed once interface is closed.
+assert.strictEqual(stream.listeners('data').length, 0);