lib: remove some useless assignments

PR-URL: #23199
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

lib/events.js

@@ -224,7 +224,7 @@ function _addListener(target, type, listener, prepend) {
 
   if (existing === undefined) {
     // Optimize the case of one listener. Don't need the extra array object.
-    existing = events[type] = listener;
+    events[type] = listener;
     ++target._eventsCount;
   } else {
     if (typeof existing === 'function') {

lib/internal/readline.js

@@ -258,7 +258,7 @@ function* emitKeys(stream) {
           s += (ch = yield);
 
           if (ch >= '0' && ch <= '9') {
-            s += (ch = yield);
+            s += yield;
           }
         }
 

lib/net.js

@@ -1071,10 +1071,6 @@ function afterConnect(status, handle, req, readable, writable) {
     return;
   }
 
-  // Update handle if it was wrapped
-  // TODO(indutny): assert that the handle is actually an ancestor of old one
-  handle = self._handle;
-
   debug('afterConnect');
 
   assert(self.connecting);