code: function onKeyEventTargetKeyDown(e) {
        var macroModeState = vimGlobalState.macroModeState;
        var lastChange = macroModeState.lastInsertModeChanges;
        var keyName = CodeMirror.keyName(e);
        function onKeyFound() {
          lastChange.changes.push(new InsertModeKey(keyName));
          return true;
        }
        if (keyName.indexOf('Delete') != -1 || keyName.indexOf('Backspace') != -1) {
          CodeMirror.lookupKey(keyName, ['vim-insert'], onKeyFound);
        }
      }
docs: Handles raw key down events from the text area.
  - Should only be active in insert mode.
  - For recording deletes in insert mode.