fix typo

node_modules/ace/lib/ace/lib/event.js

@@ -244,7 +244,7 @@ function normalizeCommandKeys(callback, e, keyCode) {
                 if (pressedKeys[keyCode] == 1)
                     ts = e.timeStamp;
             } else if (keyCode === 18 && hashId === 3 && location === 2) {
-                var dt = e.timestamp - ts;
+                var dt = e.timeStamp - ts;
                 if (dt < 50)
                     pressedKeys.altGr = true;
             }