function onCursorActivity() {
      var macroModeState = vimGlobalState.macroModeState;
      if (macroModeState.isPlaying) { return; }
      var lastChange = macroModeState.lastInsertModeChanges;
      if (lastChange.expectCursorActivityForChange) {
        lastChange.expectCursorActivityForChange = false;
      } else {
        // Cursor moved outside the context of an edit. Reset the change.
        lastChange.changes = [];
      }
    }
Listens for any kind of cursor activity on CodeMirror.
- For tracking cursor activity in insert mode.
- Should only be active in insert mode.